The Doctor enters the TARDIS and hangs his fez on a lever on the console. When he pushes another lever the fez vanishes. A time portal appears behind him and Albert Einstein comes through it with the Fez. Einstein says that he had been working on his own time machine but suddenly arrived in the TARDIS. The Doctor says that the fez was Einstein's and the TARDIS must have recognised this and created the portal by accident. Einstein is holding a jar of green liquid which he claims is bionic fusion liquid, the last component of his time machine. The Doctor scans the liquid and suggests that his friend has got it wrong. He says that he will run some tests on it but Einstein says he wants to do that himself. Einstein turns away from the console and the jar bubbles over causing the liquid to splash onto Einstein's face. He transforms into an Ood. His eyes are red and he repeats, "Death is the only answer."
The Doctor makes a few adjustments to the controls and creates an energy field that turns Einstein back into a human, albeit with wilder hair which the Doctor admires because it looks "more sciencey". He scans Einstein and determines that he walked into the TARDIS on 18 September 1945. He drops the scientist off on that day and sets off for another adventure. As the Doctor walks away from the console he passes a blob of the spilled liquid from Einstein's jar. It begins to move on its own.