In this last gasp of the "Carry On" series, minus most of the "Carry On" players, Jim Dale plays Spanish map-maker Christopher Columbus, who has a plan to navigate a new route to India, bypassing the Sultan of Turkey (Rik Mayall) and his sky-high tributes. He convinces King Ferdinand of Spain (Leslie Phillips) and Queen Isabella (June Whitfield) to finance his trip, and he sets off for points east with a cabin boy in tow. But what Columbus doesn't realize is that his cabin boy is, in fact, a cabin girl.