The episode is mainly about a chess grandmaster who admits to his wife he will kill her and get away with it. She fears for her life and pays Monk to prove he is the murderer. Unfortunately, the wife dies soon afterward. Being a chess genius, Monk and the police department are unable to prove he killed his wife. Monk and the cops do discover that he had been married before, and the first wife died in a similar unexpected way. Monk soon becomes angered that he can't prove anything that he considers planting evidence.
Overall, I thought this episode was pretty good. David Strathairn was excellent as a cold-blooded killer. Obviously, Monk does manage to prove the wife was murdered. My one complaint was the ending though. I thought that a chess champion would find a more clever way of killing his wife, however.