Peter Cheyney 
They Never Say When [EPUB ebook] 

Slim Callaghan, private detective, is drawn into a particularly dubious case — even for him. A Mrs Paula Denys says she paid a man to steal the priceless Denys Coronet from her husband’s safe. Now the thief won’t hand over the goods and is attempting to blackmail her. Callaghan solves the problem for his client but, too late, discovers the luscious Mrs Denys is not all she seems. Callaghan is determined to get to the bottom of it all — and opens some dangerous cans of worms in the process.