They're locked up for your safety.

Now, you're locked in with them.

Dr Connie Woolwine has five days to catch a killer.

On a locked ward in the world's highest-security prison hospital, a scream shatters the night. The next morning, a nurse's body is found and her daughter has been taken. A ransom must be paid, and the clock is ticking.

Forensic profiler Dr Connie Woolwine is renowned for her ability to get inside the mind of a murderer. Now, she must go deep undercover among the most deranged and dangerous men on earth and use her unique skills to find the girl - before it's too late.

But as the walls close in around her, can Connie get the killer before The Institution gets her?

A claustrophobic, haunting crime thriller that will keep you up at night, perfect for those who couldn't put down The Sanatorium and Amy McCulloch's Breathless.