Skeletons in the Closet - Jean-Patrick Manchette

Eugéne Tarpon, the private-eye protagonist from Manchette's No Room at the Morgue, appears once more for a characteristically brisk and brutal story full of unexpected comedy and feeling.
Private eye Eugéne Tarpon is back to sleeping in his office, waiting for a paying job to turn up. Then he gets a call from a sometime contact in the police department. He's referring a nice old lady-a distant relative-to Tarpon; her daughter's gone missing and, the copy says, there's no finding her. There are no leads. She's gone. But the old lady's pigheaded. Do me a favor, he tells Tarpon. Humor her. Take her off our hands. Take her money, too. And, by the way, there's no need to investigate the actual business at all.

Tarpon may be down and out, but he's too much of a gentleman for that. Plus, fed an obviously fishy story, he doesn't have it in him to let well enough alone.

Once again, Tarpon is making a very big mistake.