The prisoner of Guantánamo

An FBI agent, fluent in Arabic and good at interrogation, has been put to work at Guantanamo, where he has been ordered to turn a blind eye to some of the interrogation techniques in use by other government entities that go against FBI standards. A soldier drowns and washes up on Cuban soil under mysterious circumstances and the agent is put in charge of the investigation. When a trio of spooks shows up, including an old friend, it seems there's something very strange going on, and seems connected to a mistake the agent made many years ago that put him between Cuban agents and US policy. Fascinating setting, strong characterizations - an all-around excellent book.