The Golden Goose — Ellery Queen

An orphan encounters greed, deception, and murder when she goes to live with a new family

Despite her name, Princess O'Shea is not a spoiled brat. When her father's death leaves her an orphan, she goes to live with her old uncle, Slater, and is horrified by what she finds. She knew the O'Sheas were a family of scoundrels, but Slater and his awful brood are the laziest bunch of nitwits she has ever met. From her moronic cousin Twig to the daffy Peet, every one of Princess's new relations is driven by greed, lust, and a desperate fear of work. The only thing holding them together is the promise of their father's fortune -- and Uncle Slater is not long for this world.
 
When Princess finds Slater lying facedown on his bedroom floor, she assumes he's sleeping off a bender. In fact, he will never wake again. His bourbon was poisoned, and if Princess isn't careful, she'll be the next O'Shea to die.