A woman who hates boats sets Philip Marlowe into motion on his next mystery. A man in a dark room hires Marlowe to check up on his wife, Ona Estabrook. It's not worries about divorce, but Mr Estabrook suspects his wife is in danger.

Marlowe doesn't beat around the bush, but when he confronts the former dancer in a Mexican bar, he ends up face to face with a thug with a knife. Why does he want to know Marlowe's business with the woman>? When Philip wakes up, he's in the hands of a friendly tourist named, Roman. A body turns up, but who is the mysterious killer?

The chase is on to see who has a hold over Ona, and cause to overcome her fear of being on boats to meet with them. Has he found Dolph Bently? Who is the latest man waving a gun in Marlowe's direction? Is Roman more than just a tourist who keeps bailing Marlowe out of trouble? The answers aren't apparent to Marlowe, but in epilog he tells how the tangled mess all shook out.