Two stories in one. In Dragon's Teeth, Ellery Queen is persuaded by a reckless young man named Beau Rummel to set up a private detective agency on the understanding EQ will lend only his name. Then an eccentric multi-millionaire who has lived on his yacht for years comes in and retains Queen for mysterious services to be named later. Shortly afterward the millionaire dies allegedly of a heart attack and is buried at sea. EQ is stricken by an emergency appendectomy and so Beau has to pretend to be EQ and investigate.
In Calamity Town EQ is investigating a poisoning in the wealthy Wright family, for whom the town of Wrightsville is named. There are several EQ stories set I the self-consciously all-American small town of Wrightsville. I like some of the short stories, but not one of the the novels. I have not tried this one yet. ( )

While I didn't solve The Dragon's Teeth, I did solve Calamity Town before the big reveal by Ellery Queen. I thought the solution was obvious, but it was a good read. ( )