Cool & Lam Mystery #29 (1970)

The client's card reads simply "M. Calhoun." Like so many others, he comes across all dismayed to learn that Cool is a woman and Lam is a runt. Only after he pays a standard retainer and exits the office do Bertha and Donald unmask the man behind the "M.": filthy rich Milton Carling Calhoun II. And the receptionist swears he came in specifically asking for Mrs. Cool. The agency has been hired by him to locate a writer named Colburn Hale, who seems to have cleared out of his apartment overnight, leaving no trace. Calhoun claims he just wants to have a chat with Hale. Yet, when Donald reports that he's been able to track the writer's supposed girlfriend, Nanncie Beaver--a woman Calhoun never so much as mentioned--down to the Mexican border town of Calexico, the client hotfoots it down by car, overnight, in a pouring rainstorm. Then Frank Sellers, of LAPD's Homicide Division, unexpectedly joins the Calexico party. And that's when Donald's case really goes south.