Escaping from China with a microfilm of the formula for the mysterious "Lotus X", Lord Southmere, a Queen's Messenger, is chased by a group of Chinese spies.
| Actor | Role |
|---|---|
 Derek NimmoLord Southmere | Lord Southmere |
 Hugh BurdenHaines | Haines |
 Bernard BresslawFan Choy | Fan Choy |
 Helen HayesHettie | Hettie |
 Joan SimsEmily | Emily |
 Deryck GuylerHarris | Harris |
 Clive RevillQuon | Quon |
 Molly WeirScots Nanny | Scots Nanny |
 Max WallJuggler | Juggler |
 Natasha PyneSusan | Susan |
 Joss AcklandB.J. Spence | B.J. Spence |
 Peter UstinovPrince John/ Hnup Wan ''Hunp'' | Prince John/ Hnup Wan ''Hunp'' |
 Jon PertweeColonel | Colonel |
 Joan HicksonMrs Gibbons | Mrs Gibbons |
 Amanda BarrieMrs BJ Spence | Mrs BJ Spence |
 Percy HerbertMr Gibbons | Mr Gibbons |
 Arthur HowardThumley | Thumley |
 John LaurieJock | Jock |
| MMax HarrisTruscott | Truscott |
| AAndrew DoveLord Castleberry | Lord Castleberry |
 Frank WilliamsDr. Freemo | Dr. Freemo |
 Aimée DelamainMillicent | Millicent |
 Roy KinnearSuperintendent Grubbs | Superintendent Grubbs |
| LLeonard TrolleyInspecter Eppers | Inspecter Eppers |
| JJoe RitchieCabbie | Cabbie |
 Angus LennieHamish | Hamish |
 Kathleen ByronColonel's Wife | Colonel's Wife |
 Lucy GriffithsAmelia | Amelia |
 John BardonBookmaker | Bookmaker |
 Jane LapotaireMiss Prescott | Miss Prescott |