I step out of my hiding place; now comes the thrill. My hand goes around his neck as I pull him close. He struggles, and his shoes skid across the walkway. Then I push. The splash resonates around the silent canal, but he never makes a sound.

There isn’t a serial killer stalking the canals of Detective Sergeant Carrie Flynn’s hometown of Manchester. That’s what the police tell the local community, but Carrie knows that just isn’t true. Six years, a dozen victims…Carrie spends every night alone in her flat, going back over the hundreds of files, looking for the missing clue.

Now, another person has vanished, only this time the police haven’t found a body. Carrie knows all too well what it feels like to have someone you love disappear without a trace. Her sister has been missing for 20 years, and Carrie will never stop searching for her.

The victim’s relatives are distraught, and Carrie has no answers to give them. But why does the mother not want to answer questions? Who is the mysterious girl next door? What secrets are this family hiding?

Then Carrie finally gets a breakthrough; years ago, she caught a glimpse of the killer and the distinctive tattoo on his arm. When she finds a picture of this tattoo, she knows she’s close at last. Carrie wasn’t there when her sister needed her most, but she will spend the rest of her life making sure no more twisted souls walk free.

Can she finally solve the case that has cast a long shadow over her career, and will the demons in her own past help her to catch this deadly killer?