The girl emerged from the woods. Traumatised and emaciated; close to death, but alive. Her story seemed too terrible to be true. But it was. Every dreadful word of it. When, days later, another desperate survivor is found, a pattern becomes clear. Pairs of victims are being abducted, imprisoned then forced to make a terrible choice. Which would you sacrifice – your life or your conscience? For DI Helen Grace there is now an unseen killer to be hunted down.