Professor Shakeshaft is giving a lecture on Alchemy – he demonstrates how to make liquid gold, and starts to talk about “Misgone Magic,” or the Fosters’ Effect.  Tim and Azmat are teasing him about how he knows all this stuff from the Middle Ages, when vapours from the experiment get the better of the Professor and he collapses.

Thunderblast and Beetle ask Shaky if there’s a problem – he keeps on having accidents.  He spent one lecture the day before talking in Medieval French!  Shaky insists there’s nothing wrong with him, and he is taken off to bed.  Meanwhile, the students are deliberating about how old Shaky actually is.  He claims that he is 600 years old, and Azmat thinks he’s a bit crazy.

Ethel and Hobbes are trying time-travel experiments in the laboratory.  They successfully turn back time a few seconds, but Ethel is fed up.  She decides to call it a day, but Hobbes wants to carry on.  Ethel asks him if he is working so hard because he is going in for the Capernicus Prize.  Hobbes doesn’t know what this is.  Ethel explains it’s a prize awarded yearly to the student with the most original piece of research.  Hobbes doesn’t care; he just wants to control time.

Milly goes to Shaky’s room to see how he is, and finds him staring a painting of a woman.  Shaky thinks that the Beetle wants him to go into a nursing home, and refuses to take his potions.  The picture that Shaky is looking at is of a woman he once knew – 600 years ago.  Her name is Alison.  Milly asks what’s wrong, but the Beetle walks in and interrupts.  She thinks that he is depressed, and the Beetle traps her into watching over him during the night.

During the night, Shaky is up and about.  He wakes Milly up and she follows him.  He takes the painting to the cellars of the college.  Shaky catches her following.  Milly asks where they are.  Shaky explains that they are in the Foundations of the College, in his secret study.  He says that he wants to time travel back to when he was young.  This makes him about 570 years old!  Milly doesn’t believe it.  It has something to do with Alison – she and Shaky were engaged once.  He wants to go back and see her again.  He only has a window of time in which to travel.  If he can’t go on Thursday at midnight, he may never have another opportunity to go back and see her.  Milly suggests stealing some of Starfinder’s notes on time travel.  She goes up to his lab, but Hobbes is still there, working.  He hides himself, and then follows Milly back to the cellars.  Shaky realizes that between them, he and Starfinder have enough information to solve the problem of time travel.  Hobbes is outside the door listening, and hears everything.

Four days later, Thunderblast and Beetle can’t understand why Shaky is always asleep.  Beetle suggests that he is past teaching, but Thunderblast doesn’t want to get rid of him.  In the cellar, Hobbes is copying Shaky’s time-travel spell.  He hears someone approaching, and hides.  It’s Shaky.  Milly turns up; she is coming back in time with Shaky.  He recites his spell, and they travel back in time.  They are still the same age, and in the same place, just 600 years ago.  They walk into a party – Shaky’s engagement party.

In the cellar, Hobbes turns up in a white cloak.  In the Hall, Shaky sees Alison, all his old friends, and him when he was young.  Guy, one of Shaky’s friends turns up.  He has news for the young Jonathon about their experiments.  They have found the secret of the Elixir of Life – it involves Sorcerer’s Eggs.  Guy wants them to drink the Elixir, before someone else steals their secret.  Milly realises that this is why Shaky is this old.  Drinking the Elixir was the big mistake he has spoken of.  Alison doesn’t want him to drink it, but he ignores her.  Milly runs off to try and stop him taking the potion, but is too late and arrives just after they have downed their goblets.  She goes back to the party to tell old Shaky and Alison the bad news.  Alison runs off in distress.

Shaky and Milly realise that they can’t change the past – Shaky is content now that he has seen Alison and he is happy to go back to the present.  Hobbes walks into the laboratory where Guy and Jonathon are sleeping.  He discovers Guy’s notebook, and steals it and escapes just before the men wake up.  Milly and Shaky return to the 21^st Century, and Shaky rips up the time travel spells.  As Milly goes to walk back to her dormitory, she sees a mysterious figure in a white cloak.  The next day, Shaky is back to his old self.