This happy-go-lucky British comedy has young American Cy Hallam (Tim Turner) studying British Customs and Excise methods. He is assigned by Miss Applejohn (Judith Furse) – a burly and masculine female customs officer – to investigate smuggling in the West Country seaside village of Hell.
Posing as a press agent for alluring American TV star Diana Melton (Sandra Dorne), Cy stays at an inn run by Dan Evershed (Jon Pertwee), the henchman of Bertie Bernard (Richard Murdoch), the smooth boss of the smuggling operation.
Miss Applejohn arrives, but – after some slaphappy action involving a runaway steamroller – she gets stuck into some illicit liquor and joins the smugglers. At the same time, Cy falls for Jean (Zoreen Ismail), the squire’s comely daughter, and buys Dan’s Inn.
Dan is engaged by Diana for American television and reveals that he is actually an Earl. Diana subsequently accepts Dan’s proposal, and Miss Applejohn – still tiddly – tells the Customs and Excise what they can do with their job!