When a woman discovers that her personal belongings have been disturbed while she slept in her Manhattan apartment, the police initially dismiss her complaint. Nothing has been stolen, and there are no signs of a break-in. But when the woman is later found dead, Lincoln Rhyme and Amelia Sachs are called in to investigate the murder.
They soon discover that the killer calls himself "The Locksmith." Obsessed with locks, he sneaks into other people's homes in the middle of the night and restrains his victims using intricate knots or locks before carrying out his crimes...