Threatening letters arrive in the mail over a period of weeks, ending with a simple declaration: "Think of any number . . . picture it . . . now see how well I know your secrets." Those who comply find that the letter writer has predicted their random choice exactly. But when oddities that begin as a diverting puzzle quickly ignite into a massive serial murder investigation, police are confronted with a baffling killer, one who is fond of rhymes filled with threats and warnings, whose attention to detail is unprecedented, and who has an uncanny knack for disappearing into thin air.

Brought in as an investigative consultant, Dave Gurney, a recently retired NYPD homicide investigator, soon accomplishes deductive breakthroughs that leave local police in awe. Yet, even as he matches wits with his seemingly clairvoyant opponent, Gurney's tragedy-marred past rises up to haunt him, his marriage approaches a dangerous precipice, and he wonders if he's met an adversary who can't be stopped.

A work that defies easy labels--at once a propulsive masterpiece of suspense and an absorbing immersion in the lives of characters so real we seem to hear their heartbeats--Think of a Number is a novel you'll not soon forget.