An explosion blasts through a cafe in Central London. Minutes later, a call from an unknown terror group warns that a far greater attack will be launched in twelve hours' time.

William Garrett, nicknamed "Fox," is awaiting trial for mass murder. He claims he can name the bombers--but only at a price.

It's a terrifying race against time for Detective Inspector Mike Bolt and Deputy Commissioner Tina Boyd as they chase their targets across the city in a desperate bid to prevent a major atrocity before it's too late...

As shocking revelations are unveiled, you'll be racing to the last page as fast as the characters in Ultimatum. As #1 New York Times bestselling author Harlan Coben says, "Simon Kernick writes with his foot pressed hard on the pedal. Hang on tight!"