The Finishing Stroke by Ellery Queen
The Finishing Stroke is set primarily at Christmas-time, but bookended by a prologue set twenty-some years prior to the main events and a wrap-up that takes place over twenty years later. The bulk of the story takes place at Christmas, 1929. John Jr. has put together an extended Christmas party at the home of his guardian, Arthur Craig. We've got an assortment of guests, including John's girlfriend, Rusty Brown and a few of their friends. There is also the family doctor, the family lawyer, a pastor and a publisher. And, of course, Ellery Queen. Sebastian announces that some important events will happen during the party. First, his book of poetry is being published by the House of Freeman. Second, January 6th is his twenty-fifth birthday and he'll come into the trust fund that his father set up for him in his will. Third, he's going to marry Rusty. There's a final item, but he's keeping that a secret...