Adapted from the play Something About a Sailor by Earle Couttie, Watch Your Stern is from the Carry On series and retains the same winning comic formula. Accident-prone Ship Stewered, Ordinary Seaman Blissworth (Kenneth Connor), manages to destroy the blueprints to a top-secret homing torpedo project. Along with his equally inadequate commanding officer, Captain Foster (Eric Barker), their only hope is to get another set bound for London. But when Admiral Sir Humphrey Pettigrew (Noel Purcell) turns up they try to cover up their mistake by presenting him with a set of plans that detail the ship's refrigeration system. When they discover a female naval scientist, Miss Potter (Hattie Jacques), is due to arrive for torpedo testing, Blissworth is forced to dress in drag and impersonate her. Blissworth's dilema is exacerbated when the Admiral himself need keeping at bay because of his amorous intentions. Excelling alongside a cast also including Sid James and Eric Sykes is Spike Milligan, as Lt Cmdr. Fanshawe Phillips his inimitable smooth and amorous self.