"A woman awakes in the morning to find that someone has picked her apartment's supposedly impregnable door lock and rearranged personal items, even sitting beside her while she slept. The intrusion, the police learn, is a message to the entire city of carnage to come. Lincoln Rhyme and Amelia Sachs are brought in to investigate and soon learn that the sociopathic intruder, who calls himself "the Locksmith," can break through any lock or security system...

Trying to discover why a Harlem high school student is being targeted for murder, quadriplegic detective Lincoln Rhyme and his protegee, Amelia Sachs, look for answers in the student's term paper about her civil rights activist ancestor.

Lincoln Rhyme and Amelia Sachs take on the investigation of a brutal triple murder in Manhattan's Diamond District. The killer, known as the Promisor, is murdering men and women midway through the purchase of an engangement ring.

Chasing down a serial killer who complicates his crimes by leaving behind evidence implicating innocent people, Lincoln Rhyme and Amelia Sachs reluctantly team up for the investigation only to find themselves rendered the killer's next targets.