Sarah calls it Lynx again telling it she encountered it in the 13th century, calling it the same ugly identical... he tells her he is Field Major Styre of the Sontaran G-3 Military Survey. It examines her face and records assessment -- she has no military justification. Roth, off the wires, runs but Styre shoots him dead. Sarah screams and it asks her why she made that disagreeable sound. He tells her he is a warrior but she yells at him, "Murderer! Murderer!" Styre tells her that the moron was of no further use. "You as a female are far more interesting."
In the pit, the Doctor finds a tree branch to get out. Something is above, moving about. He climbs up to it--it is the three men again, "Oh, it's you again. Can't say I'm delighted -- it's no use pretending."
Among the rock maze, Harry finds another space suited man manacled with his hands up, deprived of water. Harry finds a rag and wets it.
The three men help the Doctor up and tell him, "No tricks." The Doctor yells, "Behind you!" They repeat, no tricks but the machine whips out three metal wires to wrap around them and capture them. Their guns are no use on it.
Harry tells the chap he is helping that he will have to get more help to free him. The Sontaran left this man here to die.
The Doctor smells something in the pit, "Not the control line," thinking it was once an old sewer line. He can go through it.
The Sontaran has Sarah tied up sitting against a rock and knows Sarah wasn't on the Gal Sec ship. Sarah has a red circle put on her head by the monster. His reports can never be wrong, Sarah yells at him. She, to him, is a mistake and those must be eliminated. He presses a button on a device. Harry has a stick to beat him but hides as the Sontaran leaves Sarah and goes off. Sarah calls to a calling Harry, who finds her, "Hang on old thing. Don't you worry, old thing." Harry is stopped by a forcefield around her. Harry will knock his head off and grab his "bloody" keys. He goes.
G3 military assessment survey Styre reports to a Marshall via a scanner set in the rocks. He has lured humans here and found they depend on organic chemical intake but inconsistencies have arisen. The Marshall will have one final report within the hour.
Experiment 7: the female and resistance to fear goes on. Sarah sees a snake on her arm and rocks falling at her from above. She screams, then looks down and sees a living glop of mud devouring her feet. She screams again but the Doctor is there and using the sonic screwdriver to break the forcefield device which is hidden in the rocks. He gets to her and tells her what she is seeing is not real. It is too late: Sarah seems to pass out. The Doctor feels her face, "Oh Sarah." Styre returns and the Doctor attacks him, "You unspeakable abomination!" Styre hits him down, telling him he merely resurrected the things in Sarah's pathetic little mind. The Doctor gets up, fakes that Harry should fire and turns the Sontaran around. He runs but doesn't get far. Styre shoots him down, calling him, "Worm."
The machine brings the three other men to Styre, not far from his spaceship. Vural tells Styre he helped him, he was to be freed. Styre tells him he will not let him go -- a traitor to his own kind. The other two men realize Vural lied to them when he told them he was lost on that first night.
Harry checks both Sarah and the Doctor, "Not both of them." He checks the man on the rocks that was deprived of water and finds him dead, "Murdering swine." Styre returns to the dead man and reports on this experiment Five -- human resistance to fluid deprivation. The man was kept without water for 9 days and 7 hours. Harry moves to hit the monster with a stick but the Doctor grabs him from behind and covers his mouth. Styre reports that humans are also susceptible to immersion in water as Experiment 4 showed. H2O death will occur in 3 minutes if a human is submerged.
The Doctor tells Harry that the synestic lock mechanism from Nerva's rocketship that he put in his pocket, saved him -- the ray hit that. "Never throw anything away, Harry." The Doctor searches his pockets for his 500 year diary, wondering where it is. He knows he made some notes about the Sontarans in it, "It's a mistake to clutter one's pockets, Harry." "Yes, Doctor." Sontarans never do anything without a military reason.
One of the men calls Styre a lump of filth as he conducts Experiment 8 -- resistance of body tissue to excessive pressures. A gravity bar held by Erak and Krans is over Vural -- all tied by ropes to them all. It can be made to weigh more. Styre makes it weight 200 pounds--it will crush Vural soon.
The Doctor goes to the Sontaran ship but the machine comes at him. He says, "Hello," and tells the thing not to be afraid of him, "I won't hurt you. Everything's going to be all right, I won't hurt you." He lied as he points the sonic screwdriver at it and it falls on its legs and crashes to the ground.
The gravity bar is up to 500 pounds now. Styre hears a call from the Marshall and raises the bar upward, delaying the experiment. The men see a knife he left. The Marshall tells Styre the invasion fleet is held up. The Strategic Grand Council, the military leadership group, has given Styre orders for his reports and experiments. The invasion cannot go on without these.
Styre returns to the men.
Harry gets Sarah up to the Doctor, who is thinking, staring off. "Ahh, Sarah, feeling better? No, don't tell me---there's no time." He goes on to tell that the Sontarans must have some strategic advantage over their endless war against the Rutans in order to come this far to invade the Earth. The Doctor finds only one way, "I'm going to take him on in single combat. Sontarans never turn down a chance to kill somebody." Harry and Sarah protest but the Doctor tells them the Sontaran is pretty unwieldy for all his strength and not used to Earth's gravity. As he does this, the Doctor wants Harry to take the sonic screwdriver, go into the ship, and do something. He will tell him what.
The Doctor appears over the rocks as Styre continues the 8th experiment. The Doctor mocks him, telling him that those puny creatures he tortures now are not the real human warriors--he is. The ones he has been testing are the slave castes, the Doctor claims -- "Could those puny creatures conquer half a galaxy?" He is the warrior class of Earth and he dares Styre to fight him, challenging him to single combat, unless Styre is afraid. He also mocks Styre's use of a gun. Styre takes the bait and his machete and comes at the Doctor. The Doctor has a stick and fights him.
Sarah and Harry free the three men, lifting the gravity bar off Vural. Harry goes over rocks to the spaceship and opens the door with the sonic screwdriver. He goes in and targets some odd contraption.
As he does this, the Doctor and Styre battle. The Doctor falls down. Styre is weakened but promises to finish the Doctor later. He walks back to his ship but the Doctor jumps on him from a higher up rockcliff. Styre falls and drops his machete. Yet he manages to stand and knocks the Doctor down yet again. With the Doctor down, the Sontaran comes at him with the machete but Vural interferes and is hit down in his place, killed. The Doctor tackles Styre again, holding onto him until he can see Harry leaving the spaceship with the contraption. "You're weakening, Styre!" Styre yells, "Am I!?!?" He hits the Doctor down again but has lost his machete again. Styre flips the Doctor onto his back, "I shall kill you all now!" He goes into his ship. Sarah and Harry run to the Doctor, Sarah telling him that Vural is dead, "He saved your life." "I know," the Doctor claims, "Everybody out -- fast as you can!" The trio run as Styre's ship smokes. He comes out of it and falls, his face melting inward like a balloon. His body follows. He is dead, a deflated balloon. The ship blows up.
The Doctor tells Harry he did it. Harry asks, "What did I do?" The device, which the Doctor hoped was the right one, was a turide endiode bypass transformer. Sontarans feed on energy but by altering things a bit -- and removing this, the energy fed on the Sontaran. The Doctor takes care of the invasion fleet ready to pounce by going to the TV screen and telling the Marshall this is his waterloo. The intelligence mission is destroyed and the invasion plans are in their hands. The Marshall yells that they will invade but the Doctor smiles, "What? Without Styre's report?" "Next time, human."
The Doctor asks the two surviving men if they will join them on beaming up to Nerva. They will wait down here for the Nerva folk, they don't trust the transmat. The Doctor says "I mean it should be alright..." -- he, Sarah and Harry vanish. He reappears, "But you never know quite, do you?" He then vanishes, his hat on.