A Rift in Time, Part 3: From Little Acorns...

Gaius spares Stephen's life. Stephen meets Cotus, another trainee who is due to be killed in horse trials. That night John, Elizabeth and Chris break into the gladiator school, where they hear a steam engine, sixteen-hundred years before it should have been invented. Peter suspects that Gaius is responsible for the time warp. Chris manages to free Stephen, Peter and Cotus, and Peter attempts to arrest Gaius, but he escapes in a Time Pump. The trainee gladiators are released just before the Time Pump explodes, and the Tomorrow People return to the Twentieth Century. But the Lab is not there, instead, they are in a futuristic base populated by ape-like creatures. Cotus returns to the gladiator school and begins to repair the steam engine.