Dublin's Harmon Penitentiary is Europe's most dangerous jail.

Dr Frank Ryan is in charge of looking after its inmates. It's a risky job - the last doctor was murdered - but for Ryan it's also an exciting challenge.

Early one morning, Ryan receives a phone call. It's the jail. He's needed right away. Kissing his girlfriend Lisa goodbye, he leaves his high-security apartment and walks straight into an ambush. This may be it for Ryan.

Coming to, Ryan finds himself in what he assumes is a hospital. But something isn't right. Why does his nurse lock the door behind her and why hasn't Lisa come looking for him? Is Ryan now a prisoner?

Overwhelmed by confusing and contradictory evidence, Frank Ryan's investigations lead him to the penitentiary's most secure section, J Wing, and the mysterious inmate incarcerated there...