After listening to Trudy's last message, Monk finally discovers who killed his wife. Racing against time before he dies of poison, he must make a fateful decision.
Upon being reinstated, Monk hopes to help track down a serial killer. However, he discovers that he is instead assigned to desk duty to ease himself back into his position. However, when the serial killer is caught, Monk begins to realize something is amiss.
Sharona Fleming stops by to visit her former employer while dealing with the legal matters involving her uncle's accidental death, but Monk soon begins to suspect that the accident was anything but.
Monk is forced to attend Dr. Bell's group therapy sessions, and he begins to suspect that a murderer in the group might be going after the other patients.
Natalie suspects a theater critic is responsible for a murder, despite the fact that he was present to review her daughter Julie's play at the same time the victim died.
Monk and Natalie are stranded in a small desert town and the detective spots a UFO. He soon discovers himself the center of attention, and is called in to investigate a dead woman discovered in the desert.