The UCOS team investigates the death of Eric Trimble, a soldier who was beaten to death in 1991. Their informant tells them that he and Eric, while still in the Army, were part of secret medical experiments that left the survivors paranoid. Their attempts to investigate those experiments come up against a military establishment that puts every possible in their way, including a visit from MI-5. As the investigation continues however, they discover several other possible motives including the fact that Eric was a bully and also gay. The fact that he is black also makes race a possible motive. Meanwhile, Brian continues to struggle with his alcoholism.