Forty years before his private helicopter took a fatal plunge into Lake Tahoe, Albert Crocker Vansittart drew up a will leaving his family fortune to ``the girl on the cover of Death in the Ditch.'' In order to win International Surety a million- dollar finder's fee, Hobart Lindsey has to identify the cover girl before the contingent heir, the World Fund for Indigent Artists (WFIA), sues his company and pockets the million along with the rest of the estate. Aided by his main squeeze, Berkeley Homicide cop Marvia Plum, Lindsey has a fine timeand you will tootracking the model through the thickets of pop culture (the world of early paperback originals and their collectors) and 20th-century history (since her past improbably cuts across both the Spanish Civil War and the McCarthy hearings). But his hunt takes on a darker side when his old nemesis, Nathan ben Zinowicz, pops up as executive secretary of the WFIAand the trigger man who's equally hot on the trail of 1951's hottest pulp fiction pinup. Lindsey's romp through a collectors' world that Lupoff knows as well as anybody ends about fifty pages too soon. But fans of Lindsey and Plum's first four adventures (The Bessie Blue Killer, 1993, etc.) will keep reading for a startling series cliffhanger.