The agents are sent to investigate the disappearance of several eminent scientists—the only link is that all of them have theoretically been seconded to a non-existent "Project Zero". Richard goes undercover as an electronics expert and makes it to the underground base, but is discovered and has to pose as a journalist looking for a story. Craig and Sharron are forced to follow him in.

A spy is captured at a foreign embassy but manages to dispose of the film, hiding what he was doing there. Craig is placed undercover as his cellmate so that he can arrange an escape, take the man with him, and find out who is employing him.