Meet Scott Cullen, a detective working in Edinburgh's murder squad. Young and headstrong but determined to do what's right, he's given a case that hits close to home. Think you're safe online? Think again. DC Scott Cullen of Lothian and Borders CID has only been in the job three months. Young, eager to please and desperate to do good. So a missing persons case should be an easy case to solve. Right? Fresh from a messy divorce, Caroline Adamson's future is finally looking up. Her son seems happy and she's dating again. Trouble is, Cullen can't find Caroline or the man she met on Schoolbook, the latest social network taking Edinburgh by storm. When Caroline's mutilated body is found, Edinburgh faces the reality of a serial killer hunting young women. The discovery of a second, connected victim leads DI Brian Bain to put Caroline's ex-husband in the frame. Cullen isn't so sure and is determined that the right person faces justice. As things take a personal turn, Cullen must look closer to home for the answer — before it's too late.