Amidst the thaw of glasnost, the Kremlin discovers that two Soviet agents, sent to England under deep cover in 1965, have been "lost." A beautiful and ambitious Russian agent, sent to London to track them down, becomes embroiled in a tangle of CIA, KGB and MI-5 plots and counter-plots as the two lost agents, now utterly assimilated, try to avoid detection.
| Actor | Role |
|---|---|
 Nigel HaversJeremy Coward / Sergei Rublev | Jeremy Coward / Sergei Rublev |
 Warren ClarkeAlbert Robinson / Vladimir Zelenski | Albert Robinson / Vladimir Zelenski |
 David CalderVictor Chekhov | Victor Chekhov |
 Michael GoughAndrei Zorin | Andrei Zorin |
 Joanna KanskaMajor Nina Grishina | Major Nina Grishina |
 Christopher RozyckiOleg Petrovski | Oleg Petrovski |
| RRichard HuwIgor Kostov | Igor Kostov |
 Alan DavidK1 | K1 |
 William ChubbGeorge Wetherby | George Wetherby |
 Angus MacInnesBill Sullivan | Bill Sullivan |
 Ricco RossKarl Richfield | Karl Richfield |
 Annie HulleySandra Robinson | Sandra Robinson |
| TTara MoohanSharon Robinson | Sharon Robinson |
| CCandida GubbinsAlison | Alison |
| JJane NashSerena | Serena |