Who WAS that gorgeous model? When a helicopter loses power and plunges into the icy waters of scenic Lake Tahoe, killing its only passenger, millionaire Albert Crocker Vansittart, what looks like a routine claim against a life insurance policy turns into a mystery for investigator Hobart Lindsey and his sometime collaborator Marvia Plum. The reason: half a century ago, the youthful Vansittart had come across a hardboiled mystery novel and become obsessed with the glamorous model who'd posed for the cover painting. Now, Vansittart's multimillion dollar policy is to go to