Frustrated butcher Fred Ramsden (Windsor Davies) and his dim electrician friend Ernie Bragg (Jack Douglas (actor)) happily head off for a holiday trip at the Riverside Caravan Site, while their respective wives Sylvia (Liz Fraser) and Vera (Patricia Franklin) look forward to their health farm holiday. Once at the caravan site of Major Leaper (Kenneth Connor), Fred starts making eyes at two young female campers, Carol (Sherrie Hewson) and Sandra (Carol Hawkins). However, as Ernie talks in his sleep and any infidelities are likely to be spoken of in the marital bed after their holiday, Fred is despondent. Professor Roland Crump (Kenneth Williams) teams with Roman expert Anna Vrooshka (Elke Sommer) in an Excavation (archaeology) at the site. Arthur Upmore (Bernard Bresslaw) and his wife Linda (Patsy Rowlands) are saddled with her mother Daphne (Joan Sims) and her vulgar mynah bird. Arthur is caught in a compromising position with attractive blonde Norma Baxter (Adrienne Posta) whose husband Joe (Ian Lavender) is lumbered with their giant wolfhound. After a few pints with the amused pub landlord (David Lodge (actor)), Fred and Ernie discover that the caravan site is riddled with excavation holes. Daphne is perturbed by the discovery that her estranged husband Henry Barnes (Peter Butterworth) lives a downtrodden life as the camp's odd-job man, despite having won the Football pools. Major Leaper is determined to give the place a boost and arranges an evening cabaret for the caravanners, but a mix-up over the phone secures a stripper, Veronica (Jenny Cox), rather than the singer he wanted. Carol and Sandra having hooked up with archaeology students Bob (Brian Osborne) and Clive (Larry Dann), Fred and Ernie pick up Maureen (Diana Darvey) and Sally (Georgina Moon), two beautiful young women from the village. Some wet paint, some glue, heavy rain that causes the tunnels of the dig to collapse, and the arrival of their wives soon bring their planned night of passion to a halt.