While the FBI and Homeland Security struggle to determine who's behind the carnage, Lincoln Rhyme and Amelia Sachs race to decode the forensics in order to prevent the next assault.
But all is not what it seems. Lincoln Rhyme soon finds he's up against a merciless killer with a unique weapon - one that can be found in everyone's home and office.
What's more, one of the few criminals to have ever slipped Rhyme's net is back in operation. Working in Mexico, the deadly assassin known as the Watchmaker has set his murderous sights on more innocent victims, whose identities are as yet unknown . . .
Lincoln Rhyme must race against the clock, juggling the two investigations, as they hurtle headlong toward their deadly outcomes.