Despite a promising premise, this latest Karen Pelletier mystery is more academic than smart. Pelletier, associate professor of English at prestigious Enfield College, causes a sensation by telling reporter Marty Katz that the best novel of the 20th century is Mildred Deakin's Oblivion Falls, a controversial and once-popular '50s potboiler of youthful sex and death. After Pelletier's quote appears in the New York Times, Oblivion Falls becomes an Oprah book and shoots to the top of the Times bestseller list. Deakin disappeared soon after the novel's publication; Katz spies a story and begins digging into the past. His untimely death on Deakin's doorstep in upstate New York thrusts the author (now a goat farmer) back into the limelight as the prime suspect in Katz's murder. Pelletier, who feels guilty for starting the chain of events that led to the murder, investigates. The three previous Pelletier novels (Agatha-nominated Quieter Than Sleep, etc.) have an easy, conversational tone and a sassy, engaging heroine. Unfortunately, the series seems to have run out of steam. The secondary characters have become easily recognizable stereotypes; the soft-boiled plot is formulaic and bland. The predictable confrontation between Pelletier and the two-dimensional murderer at the climax falls exceptionally flat. Agent, Deborah Schneider. (Dec. 26) Forecast: More outings like this one could threaten Karen Pelletier's shot at tenure in the mystery world. While fans of Dobson's previous novels will buy this one, most of them will be disappointed.