While being chased by the customs officials as smugglers, the  Doctor and Romana work to both track down the smuggler and to separate the two ships. During all this excitement, multiple Mandrels have escaped from the CET machine and the Doctor discovers their secret.

The Doctor decides to modify some of the TARDIS's systems, so disables most of the major ships systems. During this process, they encounter a stranded ship from Skonnos. They the assist the remaining crew member who then kidnaps Romana and leaves the Doctor stranded in the TARDIS.