The Stranger (Colin Baker) arrives at a remote station in a steam engine, which promptly disappears. He has lost all memory of his identity, as has his companion, Miss Brown (Nicola Bryant). Their only other company is an eccentric bowler-hatted commuter, who is anxious to prevent them from breaking through a wall situated in the bowels of the station.
The Stranger (Colin Baker) arrives on Earth with no memory of who he is or why he's there. However, two men on a secret mission seem to know his identity and the owner of a local bar/club seems to be hiding a secret in an upstairs room. Unsure of whom to trust or even believe, The Stranger must try and unravel the threads of his mysterious past...a past he may not want to remember.
A reluctant Solomon (Colin Baker), along with his former associates Egan (David Troughton) and Saul (John Wadmore), have (they think!) escaped Earth and returned to their own dimension. But a mysterious force returns them to Earth and drops them right into the middle of a top-secret experiment involving a young girl's mind powers. They soon find that the experiment has gone wrong and unleashed something deadly...and unless they can find a way to stop it, they and the experiment's team members will all soon be dead!