A member of British Intelligence assumes a fictitious criminal identity and allows himself to be caught, imprisoned, and freed in order to infiltrate a spy organization and expose a traitor.

In Venice, the millionaire benefactor Cecil Fox watches a Seventeenth Century play ‘Volpone’ and plots a practical joke to play on his three former greedy mistresses. He hires the unemployed actor William McFly to act as his butler and stage manager and sends letters telling the mistresses he is terminally ill. The prime intention of Rex is to see the reaction of the women after the reading of his will but things do not go as planned.