DCI Jane De Freitas's personal fallout with boss and partner chief superintendent Robert Drake is the least of her worries when three people are shot dead in a petrol station. Nikki and Jack conclude that it is the work of a concealed shooter from long range. A sniper is at large in London. They combine ballistics and wound pathology, along with DCI De Freitas's expertise in victim and killer profiling, to narrow down the suspects. De Freitas contains her undercurrent of animosity towards Drake, as the team work to find the killer apparently striking at random.