In the dead of night, three raging fires light up the city skies. It's more than a tragic coincidence. For DI Helen Grace the flames announce the arrival of an evil she has never encountered before. Because this is no firestarter seeking sick thrills, but something more a series of careful, calculating acts of murder. But why were the victims chosen? What's driving the killer? And who will be next? A powder keg of fear, suspicion and dread has been laid. Now all it needs is a spark to set it off . . .