Britain is at war and Inspector Hornleigh (Gordon Harker) wants to join the hunt for fifth columnists but instead he and Bingham (Alastair Sim) are sent undercover into the army to find out who is stealing army jam!
However, soon Hornleigh is on the trail of suspected nazi spies, the trail leading to a suspicious dentist then an even more suspicious school and then a thrilling finale on a Royal Mail train...
It is a shame they never made any more Hornleigh films as Harker and Sim had great chemistry together and the film has a perfect mix of serious police work and humour.
