In ancient Britain, square-wheel-maker Hengist Pod is among those captured by the Roman forces of Mark Antony and taken to Rome where he is sold in the slave market. He and his friend Horsa manage to escape and find refuge in a temple where they are welcomed with open arms by the sex-starved Vestal Virgins. Sought by troops, Horsa does mighty deeds with his sword before making his escape. Left behind, the weak-kneed Pod is thought to be the valiant warrior who has saved the life of Caesar, and the latter promptly appoints him his bodyguard. Thus Pod becomes the fear of all - except Mark Antony, who guesses the truth. Caesar sends Mark Antony to Alexandria with instructions to dispose of Cleopatra and instal Ptolemy on the throne of Egypt. But Cleo and Mark hit it off so well together that Mark disposes of Ptolemy instead and, returning to Rome, induces Caesar to visit Cleo with the intention of assassinating him. The conspiracy collapses in unexpected but lively fashion, with Pod once again getting credit where no credit is due. Hengist Pod is able to return with his friend Horsa to Britain where (thanks to a love philtre which was the property of Cleo) his shrewish wife finds him a completely changed man.
"Based on an idea by William Shakespeare", runs the legend immediately following the script credit, which suggests a level of wit never quite reached by this latest and pictorially most ambitious of the "Carry On" series. In fact the film is funny in the usual bludgeoning manner which has made the series so popular: the punning aspects of, for instance, slave auctioneer Marcus and his business partner Spencius, the lavatory jokes and the occasional blue line that one wonders if the censor noticed. Most of the players have their moments, although these are perhaps too few for some old stalwarts like Joan Sims. Amanda Barrie, however, as a comically suburban Cleo makes a worthy addition to the team.