A dog with a spying device under its skin is sent to the Russian government as a present. When the Russians send the dog to a veterinary, British intelligence must get to the dog first and retrieve the spying device.
| Actor | Role |
|---|---|
 Laurence HarveyDr. Francis Trevelyan | Dr. Francis Trevelyan |
 Daliah LaviPrincess Natasha Romanova | Princess Natasha Romanova |
 Lionel JeffriesStanley Farquhar | Stanley Farquhar |
 Eric SykesWrigley | Wrigley |
 Eric PortmanBritish Ambassador | British Ambassador |
 Denholm ElliottPond-Jones | Pond-Jones |
 Colin BlakelyRussian Prime Minister | Russian Prime Minister |
 Robert FlemyngM.I.5 Director | M.I.5 Director |
 June WhitfieldElsie Farquhar | Elsie Farquhar |
 Bernard ArchardRussian Intelligence Chief | Russian Intelligence Chief |
 Paul FordAmerican General | American General |
 Michael TrubshaweBraithwaite | Braithwaite |
 Wanda VenthamMrs. Winters | Mrs. Winters |
 Marianne StoneMrs. Whitby | Mrs. Whitby |
| AAmy DalbyMiss Marchbanks | Miss Marchbanks |
| JJohn Forbes-RobertsonM.I.5 Workshop Director | M.I.5 Workshop Director |
| RR.S.M. BrittainCommissionaire | Commissionaire |
| PPeter BaylissProfessor | Professor |
 Barry CryerHarold Wilson (voice) | Harold Wilson (voice) |
 Renée HoustonLady Blanchflower | Lady Blanchflower |