The Ancient Covenant that separates the Six-Fold Realm from the ordinary five dimensions of the Universe also forbids union between the Chronovores and the Eternals; however, Prometheus the Chronovore and Elektra the Eternal have defied the covenant to bear a child, an Avatar they hope will unite all of the races of all of the dimensions of the Universe. But at the moment of conception, they are found by the Guardians, the Six-Fold-God of the Six-Fold-Realm. The Guardians unmake Prometheus' timeline so he never existed, and the Avatar is taken from Elektra and confined at birth. The Chronovores insist that it is a blasphemy which must be destroyed, but the Guardians will not take a life as unique as this. Instead, the Avatar will be bound in a crystal fragment of the Key to Time, to be freed only if necessary. If it is released before its time, madness, death and chaos will result...
The Master is fleeing from a disastrous alliance with the Krotons, renewing the damage to his body with the last embers of the Source of Traken, when his TARDIS comes under attack by forces almost beyond his comprehension. It seems the Chronovores are seeking revenge at last for the capture and abuse of Kronos. How can he protect himself against the gods themselves, when his long-overdue death is catching him up in any case? The desperate Master pieces together lost and forgotten technologies from various races, and with the last discovery of the Kirbili and the secrets of the Matrix -- which he has plundered to his leisure in the past -- he finds a way to destroy the Chronovores and prolong his own life. Only one piece of the puzzle remains for him to collect, on Earth.
The Doctor has made a terrible mistake. He and Mel intervened in a civil war on Maradnias; it was nothing important on a cosmic scale, just an opportunity to prevent a few needless deaths. But the Doctor underestimated the determination of the opposing faction, and he and Mel barely escape a nuclear holocaust which leaves billions dead. The Doctor blames himself, and so does Mel, who finds she can no longer travel with him knowing the consequences of their actions. She asks him to return her to London, after the university reunion of 1999; she will try to get back in touch with her old friends and return to a normal life. The Doctor drops her off in 2003, but she's in for an unpleasant surprise when she tries to contact her friend Anjeliqua Whitefriar. Once the kindest of people, Anjeliqua seems to have undergone a complete change of personality; she has stolen the intellectual property rights for Paul Kairos' invention, the quantum lattice, and has become a multi-millionaire while Paul hasn't received a cent for his work. Mel is appalled; what's happened to her friend?
As the Doctor prepares to leave Earth, he picks up traces from an experiment tampering with potentially catastrophic forces, and recognises the quantum signature of the waves; it seems that his old acquaintance Stuart Hyde has put TOMTIT back in operation. He finds that Stuart is now a professor at the University of West London, and he hasn't fulfilled his early promise; his encounter with Kronos left him bitter and disillusioned, all too aware that he would barely scrape the surface of the universe in his lifetime. The Doctor is concerned by the change in Stuart, and assures him that TOMTIT was entirely his and Ruth Ingram's work; the Master needed their help because humans possess a spark of creativity which even renegade Time Lords lack. Somewhat mollified, Stuart admits that he didn't hand TOMTIT over to Department C-19 after all, and told his promising young student Paul Kairos all about it. Paul retro-engineered TOMTIT and built a new invention, the TITAN array, from first principles. But even Stuart doesn't know just what Paul is capable of. After unthinkingly altering the quantum settings which his partner and fiancee Arlene Cole had struggled over for days, Paul has apologised by putting them back the way they were before... which should be physically impossible.
Stuart takes the Doctor to see the TITAN array, but warns him that he's vented about the Time Lords before; Paul and Arlene blame the Doctor for dangling his knowledge before Stuart and condemning him to a lifetime of underachievement. The Doctor tries to explain that he's not here to punish the human race for curiosity; he's simply here to warn them that by probing Calabi-Yau space, the six folded dimensions which lie separate from the five dimensions of the ordinary Universe, they risk drawing the attention of the Chronovores. He realises that he's going to have to observe their next test run... but even he isn't expecting the Master to show up. Claiming to be a Serbian investor named Branko Gospodar, the Master makes an appointment with Anjeliqua, hypnotises her and arranges to observe the test of the TITAN array; once there, he alters the settings, sends a pulse into Calabi-Yau space and attracts a young Chronovore. He then flees, leaving the Doctor and Paul to close up the tunnel and banish the Chronovore from Earth, but realise that in the few seconds he had to work, the Master has upgraded the TITAN array. It is now capable of penetrating Calabi-Yau space, just as Paul and Arlene had intended -- but now the Master intends to connect the array to his TARDIS, and use it to tap the power of the Lux Aeterna, the 11-dimensional quantum foam which underlies the structure of reality. The Master will revitalise his body with the raw power of the Universe itself, and destroy the Chronovores by cutting them off from their natural food source.
While discussing the situation with Paul, Arlene and Stuart, the Doctor runs into Mel again. She still isn't ready to deal with him, but he does warn her that the Master is present at the university. Suspecting that this may explain Anjeliqua's uncharacteristic behaviour, Mel goes to confront her friend, only to see her emerging from the basement of a nearby building. When she investigates, she sees the Master stepping out of what probably isn't a cleaning cupboard. Indeed, it's his TARDIS, which she enters using the key to the Doctor's; but then the Master launches his TARDIS by remote control, intending to set a trap for the Doctor, and Mel, fearing his return, hides in its library. Meanwhile, Anjeliqua contacts the Doctor, claims to have shaken off the Master's influence and directs him to a warehouse where the Master has set up base. The Doctor suspects he's being sent into a trap, but investigates nevertheless with Paul and Stuart -- and the moment they step into the warehouse, the Master's TARDIS generates a patchwork of time fields around them. Before Stuart realises what's happening, he steps into a different time zone and gains back thirty years of his youth before the Doctor can pull him out. The Doctor then uses bits and pieces lying around the safe zone to build a time-flow analogue; the ratios between the molecular bonds resonate with the time fields, creating a temporary safe path to the Master's TARDIS. The Doctor reaches it just in time and inserts his own key, causing the Master's TARDIS to dematerialise and restoring Time in the warehouse to normal. But Paul, who was nearly cast into the Time Vortex when the safe path collapsed around him, wonders privately why the sensation felt so familiar...
The Master has taken advantage of the others' absence to hypnotise Arlene, and has put her to work on the TITAN array. By the time the Doctor returns, her work is finished, and the Master is ready to depart. The Doctor tries to time-lock the TITAN array to prevent the Master from stealing it, but fails; the Master materialises his TARDIS around the array and departs, taking Arlene and Anjeliqua as his slaves and hostages. However, Paul realises that the Master must have remained near the Earth, to use the planet as bait; and the Doctor realises that although the Master's TARDIS is shielded, he can still use TOMTIT to track down the TITAN array, as they work on similar principles. But as Stuart and the Doctor collect TOMTIT from its hiding place, Paul, apparently shaken by Arlene's kidnapping, wanders into the depths of the TARDIS... and finds a Chronovore waiting for him in the power room, where the TARDIS taps directly into the primal energies of the Time Vortex. But this is no ordinary Chronovore.
The Doctor and Stuart track down the TITAN array to the dark side of Earth's moon, in the Dusk Nave of the Midnight Cathedral -- the only surviving artefact of the Constructors of Destiny, who vanished from the Universe millions of years ago. The Doctor tries to follow the Master, but his TARDIS goes into spasm, having triggered a trap the Master set long ago, during the original TOMTIT incident. Fearing that the Doctor would link TOMTIT to his own TARDIS in order to follow him to Atlantis, the Master had infected it with the Profane Virus of Rassilon; now, three incarnations later, the Doctor has triggered the trap at last, and it causes his TARDIS to Time Ram itself nanoseconds in its own past. At the last moment, something twists the Virus into higher dimensions, cleansing the TARDIS and allowing it to send a warning to its past self through the interstitial gap created by TOMTIT. The resulting artron backlash as the TARDIS changes time frequencies catapults it across space, towards the Virgo Cluster and the Great Attractor -- a gigantic black hole which is drawing the entire Milky Way galaxy towards itself, and which is the home of something the Doctor hopes never to encounter...
Mel makes her way to the Master's power room to search for an emergency exit, but is nearly killed by the energy surge when the Master steals the TITAN array. She survives, and emerges to find herself in a vast cathedral with a statue of an angel at its centre; Anjeliqua and Arlene are working together to install the TITAN array in the nave. Unaware that she's now on the Moon, Mel stumbles out of the atmospheric bubble while searching for a way out; however, the Master observes her predicament and sends Anjeliqua to rescue her, intending to use her as a hostage should the Doctor somehow survive the Eigen-Ram. Privately, Anjeliqua informs Mel that she's shaken off the Master's conditioning, and has sabotaged the device which will link him to the Lux Aeterna -- but he is aware of her betrayal, and Arlene is still entirely under his influence. When Anjeliqua emerges from the Master's TARDIS, the Master has Arlene install her in the device as a test subject; he needs to calibrate the settings, and doesn't care that the power of the Lux Aeterna will incinerate Anjeliqua.
The area of space around the Great Attractor is riddled with gravitational turbulence and other distortions, and in order to pull himself free and return to Earth in time, the Doctor decides to Time Ram the Master's TARDIS and then pull back at the last moment. However, his TARDIS has had enough, and fights back, nearly destroying itself before the Doctor can coax it to trust him again and materialise safely. Instead of fully materialising, his TARDIS links itself to the Master's console room, where the Doctor is reunited with Mel. They emerge, along with Paul and Stuart, but they're too late; the Master has activated the TITAN array, penetrated Calabi-Yau space and summoned the Chronovores to Earth. The Lux Aeterna flows into Anjeliqua's body -- but it doesn't kill her; instead, to the Master's horror, they merge. Anjeliqua becomes at one with the quantum energies which underlie the fabric of reality. Together, they become a goddess -- the Quantum Archangel.
The Master rushes back into his TARDIS and dematerialises, knowing that he is now defenseless against the Chronovores; and as he flees, he reverts to his cadaverous Time Lord form. But the Archangel puts things right, changing history to provide the Master with a war-TARDIS he can use to fight off the Divine Host of the Chronovores, and returning the Doctor, his friends and his TARDIS to Earth. She then departs to consider how to use her new powers, and the Doctor, fearing the consequences, retreats into the TARDIS with his friends. There, they see the first sign of the coming changes; the Whitefriar Lattice the Doctor used to link TOMTIT to the TARDIS now bears a copyright symbol identifying it as the Kairos Lattice. Anjeliqua is trying to put right her past mistakes, but the fact that they can still remember the original history proves that she is not fully in command of her powers yet. When Stuart vanishes from the TARDIS and is replaced by Dr Ruth Ingram, who claims to have been there all along, the Doctor realises that Anjeliqua is rewarding her friends by changing their pasts. Now Stuart has always been an acclaimed scientist and the director of the Newton Institute, while Ruth has been given a taste of adventure. But how can Anjeliqua make life ideal for every living being on Earth?
When Mel vanishes as well, the Doctor tries to track her down but discovers that she no longer exists in this version of history. The Archangel has created a divergent timeline for Mel and Mel alone, and she intends to do the same for every living being in the Universe. But there is a limited amount of reality in the Universe, and the Chronovores exist to prune away extraneous timelines. Cut off from the Lux Aeterna, they will descend upon the alternates and feed... and consume the people whose lives are fueling the timelines. Arlene vanishes as well, and then the Master arrives, having shaken off the pursuing Chronovores at last. He has reverted to his cadaverous state and will soon be dead, but he knows that he must join forces with the Doctor to prevent the Quantum Archangel from destroying the Universe. The Doctor tries to track her down by monitoring the great computers of the Universe; even the Archangel can't calculate all of the infinite possibilities she needs to bear in mind if she's going to change the timeline of every single being in the Universe. But when his detectors finally go off, he realises that she's chosen the most dangerous computer in the Universe -- the Mad Mind of Bophemeral.
The Doctor is forced to reveal the secret of the Great Attractor -- it is the last creation of the Constructors of Destiny, a quantum supercomputer constructed of strange matter with the event horizon as its memory store, and it was designed to understand the Universe. Ignoring their brethren, and visitors from the present and future who warned that Bophemeral would bring only madness and destruction to the Universe, the Constructors listened only to a visitor from the distant past, who assured them that their creation would play a vital role in the destiny of the Universe. But when they activated Bophemeral, it went mad immediately, destroyed its creators, and declared war on the Universe. For a thousand years, the races of the Universe fought Bophemeral's robot drones, until finally, an alliance between the other races weakened its defenses just long enough for the Time Lords to trap it in a single chronon of Time, doomed to repeat the same infinitesimal moment forever. The six Guardians rewarded the exhausted and battle-scarred races of the Universe by erasing the war from their collective memory, allowing them to forget the horror of the war. Which raises the question of how the Doctor remembers it. But that's probably just a side issue; what's important is that the Quantum Archangel has penetrated the event horizon and seeks to wake Bophemeral, to add its computing power to her own omnipotence and change the possibilities for every being in creation.
Somehow the Doctor and the Master must reach the Great Attractor, without passing through the gravity distortions which caused so much trouble for the Doctor earlier. The Master suggests shifting into a parallel timeline where the destruction of Logopolis caused the Universe's heat death, and the universal gravitational constant is therefore less powerful than in the ordinary Universe. However, they're too late; as they make their approach, the Archangel frees the mind of Bophemeral, altering its perception of the past so it will no longer be insane. Together, they return to the lower dimensions, and shift the Doctor into his own ideal timeline -- one in which his people have forgiven him and he has become the President of the Time Lords. The two TARDISes career towards the sidereal barrier between the timelines with nobody at their helms, but somehow, Paul is able to reconfigure the resonance between their plasmic shells so they will survive -- which should be beyond the capability of any human being.
The Chronovores are aware that they can't simply devour the alternate timelines whole; without the Lux Aeterna, they are now the Chronovores' only source of food. Thus, they stretch out their meals, and each timeline slowly becomes corrupted before falling apart completely. Mel is the Prime Minister of England, but her Homeless Act has resulted in the death of an innocent boy -- and as the papers tear her apart, her scientific advisor, the Third Doctor, betrays the Earth to the Cybermen. Arlene is a mega-platinum, world-famous recording star... who is first attacked by a stalker, and then framed for embezzlement by her own chief accountant. Stuart becomes worried about the vast funds requisitioned by his latest research team, and discovers too late that they are the Master and the Rani in disguise; under his nose, the renegade Time Lords have constructed a genetic resequencer which will rip apart the DNA of every living being on Earth, and recombine it into an organic gestalt -- the ultimate psychic weapon. The Doctor finds himself leading his people in a losing war against an Enemy determined to exterminate them all, and discovers that his oldest friend, the Master, has betrayed them. Rather than let the Enemy rule the Universe, he prepares to activate the Slaughterhouse's ultimate weapon -- the Armageddon Sapphire, which will tear the basic particles of the Universe apart and make way for a new Universe. Once started, the destruction cannot be stopped...
Paul and the Doctor's TARDIS work together to reach into the alternate timelines, pulling out their friends and saving their lives with moments to spare in each case. Once he's back in his proper timeline, however, the Doctor realises that no human could do what Paul has done -- and Paul sheds his human guise to reveal that he is an aspect of Kronos. This has all been part of an elaborate plan for revenge against his own people -- for Kronos is the Avatar, the spawn of a Chronovore and an Eternal, bound and imprisoned for eternity within the Crystal, doomed to madness when the Master and the people of Atlantis freed him prematurely. Kronos attacked the Master in order to convince him that the Chronovores were trying to kill him, and he created Paul Kairos and altered Anjeliqua's personality in order to provide the Master with the TITAN array he required. But it all went wrong when the Master placed Anjeliqua in the array first; Kronos would not permit the death of an innocent, and he helped Anjeliqua to survive, creating the Quantum Archangel. Now he needs the Doctor's help to stop her.
Kronos has already restored the Doctor's memory of the Millennium War so he would know of the existence of Bophemeral; now, he takes the Doctor to the Moon, where the Archangel has made a deal with the Master. She will allow him to repair the TITAN array, so he can use it to banish the Chronovores back to their Six-Fold Realm before they devour all of her ideal timelines. In fact, he intends to complete his original plan, access the Lux Aeterna and become a god. But as he completes his work, the Doctor arrives and informs him that Kronos has been manipulating him all along. The Master cannot kill the Doctor, who is protected by Kronos; he must watch helplessly as the Doctor takes his place in the array and is bathed in the power of the Lux Aeterna. The Doctor then confronts the Quantum Archangel in the higher dimensions, and tries to make her see reason. He admits to his own terrible mistakes, but insists that it's by these mistakes that we learn; if every bad decision can be reversed, then life will become a series of empty rehearsals with no ultimate meaning. The Archangel refuses to accept this, and she and the Doctor do battle on a cosmic scale, with suns and worlds as their weapons...
As the Doctor and the Archangel do battle, Kronos enters the Great Attractor, seeking the back door the Constructors never had the chance to use themselves. He finds it and generates the equivalent of an epileptic fit in Bophemeral's Mind. Suddenly robbed of Bophemeral's power, Anjeliqua comes to her senses and begs the Doctor to help her put things right, properly. The Doctor convinces her to give up the Lux Aeterna, and as it flows out of her, Bophemeral and Kronos do battle -- and Kronos wills his own destruction, detonating the Great Attractor in the process and opening a gateway back to the Six-Fold Realm so the Lux Aeterna can return to its place in the Universe. As the Doctor and Anjeliqua return to their proper plane of existence, the matriarch of the Chronovores and the patriarch of the Eternals appear and reward him for his help by changing history and restoring Maradnias, as if the Doctor had never been there.
When the Doctor and Anjeliqua return to the TARDIS, Anjeliqua is the woman she was of old, not the greedy, manipulative woman who ruined Paul Kairos' life. Paul returns as well; he may only be a construct, but he's a very thorough one, and he and Arlene will live out a normal life together. Mel forgives the Doctor for his mistakes; she will continue to travel with him. The Master flees in his TARDIS, but takes the conversion equipment with him; he knows now that he cannot bend the Lux Aeterna to his will, but he can still use it to save his life. He uses the converter to bathe himself in its power as it floods back into the higher dimensions, restoring himself to full strength and life again. But as he waits for his TARDIS to recover, the Divine Host of the Chronovores descends upon him; before they return to Calabi-Yau space through the former Great Attractor, they will feast on the timeline of a Time Lord...
Source: Cameron Dixon