Reservist Tommy Smart - who has made his fortune since the war selling army surplus - arrives at an army camp, with his chauffeur/valet, for two weeks' training. Bank manager Corporal Jones is in Tommy's squad. Sylvia, Jones' daughter, wishes to marry Lieutenant Robson, a National Service officer. Smart is under the orders of his old enemy Sergeant Thickpenny and R.S.M. Brittain; various parade ground antics ensue.

Meanwhile, Scottish Private Jim Campbell and WRAC Private Sally Briggs are romantically involved, but their superior Sergeant Manners makes unwelcome advances towards Briggs. A rumour circulates that Robson desires Sally. When Robson is accused of sneaking into the womens' dormitory, Jones becomes convinced that Robson would be an unsuitable husband for his daughter.

It is Tommy, however, who is the guilty party. At the end of the training course, he manages to straighten out the misunderstanding and frustrate Thickpenny one last time before he leaves the army base.