Mark Nelson, a young police officer, has been assigned to the team of John Mercer - a legend in the force. It's a hugh opportunity and Mark is determined to make the mostt of it. But, when a tortured and burnt corpse is discovered on his first day, he has to hit the ground running.

The evidence points to a man known as the 50/50 killer - a sophisticated and meticulous serial killer who stalks young couples, subjecting them to a single night of torture and manipulation, testing and destroying the love between them. Only one of them survives until dawn.

Soon afterwards, a young man is picked up by the police, brutally tortured and with his memory in tatters. He knows only that he has escaped from the woods... and that his girlfriend is still being held captive...