Keeper of the Keys (Charlie Chan, #6)

In the 6th and final book in the mystery series featuring the Chinese-American detective Charlie Chan, we find our hero in Lake Tahoe, California. Chan has been invited as a house guest. He meets a glamorous opera singer, Ellen Landini, and she is murdered by a gunshot during a party. Her servants and four of her ex-husbands are suspects in the case, all with weak alibis. It is up to Chan to solve the murder. The clues are cryptic and misleading by the singer's own revolver, two scarves, two cigarette boxes with mismatched lids, and the actions of a little dog named Trouble. Part of the solution to the mystery involves an elderly Chinese servant named Ah Sing—the keeper of the keys. Chan solves the case in his usual understated, spectacular fashion.