Veteran Homicide Detective James "Big Jim" Donegan and his partner, Chris Hunter, have been called to the scene of their latest case, a strangled call girl who has been put halfway through a wood chipper that was left unattended in one of the city's parks.

Today Big Jim intends to use this case, like every other crime that they have worked together, as an opportunity to teach the technically brilliant but socially awkward Hunter how to be a great cop. The training, like the work, is endless. Big Jim and Chris know that they have chosen a career that is never finished, that never stops, that death never sleeps.