When cabinet minister John Hoode is murdered at his country house, his secretary, Alan Deacon, is the prime suspect and is arrested. Reporter Anthony Gethryn determines to unmask the real murderer.

Taxi driver Jim befriends Ruritanian child King Ludwig while the latter is on a visit to London. A plot is afoot by sinister forces to kidnap Ludwig, and Jim becomes caught up in the drama. After the child is abducted Jim uses all his ingenuity, including cross-dressing as a Countess and becoming involved in a car chase, to rescue him from his captors.

'Captain tries to hide accidental female passengers from admiral.' (British Film Catalogue)