The Double shuffle (original 1952; edition 1967)

Susan Gellert is an obscure dancer - blonde, beautiful and innocent, who performed onstage with a deadly cobra on her neck, and a dancer, Denny, who also appeared innocent. Susan is insured for a sum of a million dollars at the National Fidelity, where the infamous Maddux heads the Claims Department. Maddux doesn't like it one bit, and asks Steve Harmas, his investigator, to try and find out the real picture, even before something happened to Susan and any claim was made. Was it supposed to be a publicity stunt, to get Susan's name in the local dailies? But someone stood to gain an awful lot of money, if she died. And by the time Steve completed his investigations, he was sure that whoever it was, didn't intend to wait long before collecting the compensation money...