Retired psychology professor Adrian Thomas has spent a lifetime delving into other people's disturbed minds. Now he's been diagnosed with degenerative dementia, and all his thoughts are of ending his own life while he still can.

But his clouded mind clears when he witnesses a kidnapping: a teenage girl, snatched off the street and bundled into a white van. The police dismiss him as a confused old man. But Adrian knows what he saw. And he knows he might be this young girl's only hope for rescue.

His search will lead him into the chilling world of online pornography, and the elite community who subscribe to the website What Comes Next. A website where the viewers decide what happens to their on-screen hostage. A website that is about to feature a new star: a frightened teenage girl known only as Victim Number Four...