Nazi agents in the United States learn of diamonds smuggled out of Amsterdam to this country, kill the smuggler, gain possession of the ' diamonds. Ellery Queen finds the spyring, smashes it, with a little help from his blundering secretary.
An acceptable mystery fare centred around a search for a mummy, diamonds and a spy ring - William Gargan is competent as Ellery Queen, but it's Margaret Lindsay as his secretary who steals the scene with her spirited and blundering ways. It's a fun mystery, the last Ellery Queen of the 1940's. Gilbert Roland has a smallish role, but not any less important- he plays the smuggler Paul Gilette who is murdered upon arriving in the US with the diamonds.