Early March, 2020. When a body is found on a spoil heap, Mac gets the case.

Detective Inspector Calum Larsen (known as Mac) works for the Peripatetic Investigation Team based in Edinburgh. His early enquiries establish that the dead man, tasered prior to death, was involved in a joint university project to develop new software for the deployment of laser weapons on drones.

Days later, a second body is discovered on a beach; also tasered. Mac tries to avoid jumping to the conclusion that the two cases are linked… but then evidence emerges that both men were drug users, and that there was also a personal connection between the two.

Meanwhile, Mac discovers that the project has input from an aggressive, multi-national corporation, strongly committed to the extensive use of Artificial Intelligence in weapons deployment.

As the Chief Superintendent begins to put the screws on Mac to work quickly to avoid political complications, can Mac get the cases wrapped up before it’s too late?