A change in a will, a murder and a mysterious letter. The police look to a former cat burglar to aid them in the investigation.
Pre-war intelligence man Tommy Blythe interrupts his honeymoon to investigate the discovery of vital Air Ministry blueprints on a woman killed in a London road accident. The trail leads to a boarding house in Notting Hill and its varied tenants.
Old Mother Riley falls into money so goes to Paris, where she is mistaken for a spy.
An evil prison administrator cruelly abuses the inmates at his prison, until one day the tables are turned.