Firefighters tackling a moorland blaze in the Pentland Hills, outside Edinburgh, make a gruesome discovery when they find the remains of a man.

DI Calum Larsen, known as MAC, investigates and discovers that the death is no accident and has links to illegal dumping. When a second body is found, not far from the Pentlands, it becomes clear that this case also has connections to the eco-crime world.

MAC finds progress is frustratingly slow. He also has to deal with the fallout from a bad relationship with his boss, DCI Yates. And on top of all this, his young daughter is suddenly taken ill.

As his problems continue to mount, MAC begins to take serious risks which may threaten his future. And he faces three big questions:

How can he make progress on the investigations?

How will the eco-crime world respond?

And just how serious is the threat from DCI Yates?