The world's most valuable stamp is arriving in port. Reporters crowd the dock to welcome the beautiful Miss Templeton, who owns the stamp and carries it in her purse. At the same time, noted mystery writer Ellery Queen is at the dock. He accidentally tosses some flowers into Miss Templeton's lap while she is being interviewed, which is apparently a cute way to meet.
The plot develops quickly: Miss Templeton visits a hotel to meet a collector who may buy the stamp. A stranger sneaks into Miss Templeton's room, steals the stamp out of her purse...and moments later he is murdered in a side room. We don't really think Miss Templeton killed him but she did come running out of that same room with the stamp in her hand.
The murder investigation is led by Inspector Queen, with inevitable help from his son Ellery, who after all is already acquainted with the leading suspect. Other suspects include the collector, his nieces, a boyfriend....
Charlotte Henry is earnest and cute as Miss Templeton but the character doesn't offer many surprises. Eddie Quillan is a mischievous and energetic Ellery who talks nonstop. His confident banter is sometimes humorous but often merely obnoxious.
Franklin Pangborn has a moderately amusing bit as the flustered hotel manager. Wade Boteler comes across well as the irascible Inspector Queen, and this picture's best moments are probably those that feature interplay between the two Queens.
Overall, Quillan is fun in the role but not especially convincing as a master of deduction. And the mystery itself--involving counterfeit stamps, a missing tangerine, and a locked door--is hard to get too excited about.
One funny line, though: Ellery pounds on the door of a hotel room that he knows is full of cops, and says, "Open in the name of the law!"