At 9 a.m. on New Years Eve, 1999, a man gets onto the packed escalator of a metro station and fires a silenced machine gun into the crowd. He escapes without being spotted in the confusion caused by the horror of this vicious attack, which leaves dozens of killed and injured people.

One hour later, a note is delivered to the mayor: $20 million, or the writer will instruct the killer to strike again; at 4 p.m., at 9 p.m., at midnight...hundreds more will die.

The money has to be found, the ransom will have to be paid. But then a hit and run victim is identified as the mastermind behind the operation, and suddenly there’s no way of stopping the psychotic gunman killing again, and again, and again...

The only thing the FBI have to go on is the note. Parker Kincaid, forensic document expert, and agent-in-charge, Margaret Lukas, could be the only people who can stop the killer.