Formby plays a bumbling War Reservist police officer called George Carter who aspires to become a member of the flying squad. The film is set in Merseyside where the battleship HMS ''Hercules'' is being built. A group of saboteurs are planning to destroy HMS Hercules by blowing it up. George manages to foil the saboteurs' attempts to destroy HMS Hercules, saving the battleship from being blown up by saboteurs. One of the saboteurs, called "Jake", is played by Bernard Lee.