A mediocre WW II comedy set in Merseyside and starring Formby as a member of the Police War Reserve. He uncovers a plot to blow up a battleship, the Hercules
, on its maiden voyage. The police, however, think Formby is one of the saboteurs and chase him up and down the docks. Formby manages
to get the ship launched before the explosion occurs--destroying the slipway in the process.