Charade

Charade (Criterion #57). 1963 Universal Pictures.
Starring: Cary Grant, Audrey Hepburn, Walther Matthau, James Coburn, George Kennedy, Dominique Minot
Music: Henry Mancini
Director: Stanley Donen
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While on holiday, Regina "Reggie" Lampert (Hepburn), who is planning to ask her husband Charles for a divorce, meets a man calling himself (at first) Peter Joshua (Grant). Returning home, Regina discovers that everything in the house is gone, and she finds out from the police that Charles had been murdered and thrown from a train.

Meeting with a CIA agent (Matthau), Regina finds out that Charles was involved in a theft during World War II. He and several other government agents were parachuted behind enemy lines to deliver $250,000 in gold to the French Resistance. They buried it, then were ambushed by German soldiers. After the attack, Charles dug up the gold and sold it. He's dead, but the money is still missing, and the U.S. government wants it back. So do his fellow agents who survived the botched mission.

And how does Peter Joshua fit into all of this?

Charade fell into the public domain due to a legal irregularity, so basically anyone can release it for home viewing. The movie is included as a bonus feature on the DVD release for its 2002 remake, The Truth About Charlie. Personally, I would stick with the Criterion release, even if it is a whole lot more expensive than any other release of the film.