In John Verdon's Think of a Number (Crown, July), retirement is a difficult adjustment for NYPD homicide detective Dave Gurney. Even after moving to upstate New York with his wife, Madeleine, he can't stop thinking about his past successful cases. When a former acquaintance asks for help in a personal matter Dave can't resist saying yes. But the plot thickens when his friend is murdered—and murder is only the tip of the iceberg. Dave is once again after a serial killer, this time as a civilian trying to cooperate with the local authorities. The intricate plotting of Verdon's page-turning debut, along with the murder's impossible aspect, keeps up until the satisfying climax. And Gurney is one of the most true-to-life detectives to come along in a long while. His obsession with his cases, even to the point of damaging his marriage, rings true, as does his thoughtful approach to crime solving. Readers will find this one just about impossible to put down.