Finally a little different polar

Investigation marshal Teddy Daniels and Chuck Aule teammate on an island. The only building on the island this is a psychiatric hospital that much more like a jail than a hospital.
A "patient" of this "hospital" has disappeared and two marshal will find him. During their investigation, strange discoveries will bring our two marshal to ask about this prison hospital.
Finally a detective story where we do is not facing an inspector in pursuit of a serial killer.
A closed session taking an unexpected denouement.
This is not what might be called a masterpiece (which is why I do not put 5 stars), but I strongly recommend it to fans of thrillers who want to read something a little different.