The Dain Curse — Dashiell Hammett

When eight diamonds are stolen from a prominent San Francisco family, the Continental Op is called in to investigate. But the missing jewels aren't the only thing out of the ordinary. The man who reported the burglary ends up dead, ostensibly a suicide. His daughter, one of the suspects, Miss Gabrielle Dain Leggett, has a penchant for morphine and religious cults. She also has an unfortunate effect on the people around her: they have a habit of dying. Might Gabrielle be the victim of an arcane family curse? Or is the truth about her stranger and even more dangerous? 

The Dain Curse is one of the Continental Op's most bizarre cases and a tautly crafted masterpiece of suspense.