Monk takes on a case for a couple whose daughter was murdered. The culprits, according to the lone witness, were a local cult called the Siblings of the Sun. Monk goes undercover as a recruit to investigate the matter from inside the cult, but falls victim to "Father's" mind tricks. Will Monk ever return to his old, neurotic, crime-solving self?
This episode includes examples of the following tropes:
- Absence of Evidence: Monk proves that the picture of Amanda Clarke and Tom Donovan wasn't taken while he was rushing her to the hospital, as he claimed; there wasn't any blood on the seatbelt, which was clearly visible in the picture.
- Adult Fear: Mr. and Mrs. Clark have to deal with the murder of their daughter.
- Alliterative Name: The cult leader's name is Ralph Roberts.
- Becoming the Mask: Monk goes undercover as a member of Siblings of the Sun, only to buy into their teaching to the point that Stottlemeyer and Natalie have to "kidnap" him so he'll snap out of it.
- Big Secret: It turns out that "Father" did have an alibi for the night of the murder; he was in his cabin, receiving a cortisone shot from his doctor. He couldn't reveal this because part of his image is never being sick.
- Hypocrite: Dr. Kroger, while attempting to deprogram Monk, tells him that "Father" owns property all over the place, despite saying that money causes envy and envy is the wellspring of evil.
- I Have No Son!: The other cult members considered Amanda Clark dead from the moment she left the cult.
- I Resemble That Remark!: Monk contests Stottlemeyer saying he's gullible, and Stottlemeyer says that it's not just his opinion; it was Joey Heatherton's when he spoke with her. Monk asks if he really did, thus proving the Captain's point.
- Kidnapped by an Ally: Natalie and Stottlemeyer drag Monk into a car and hold him "hostage" in an attempt to break the brainwashing. He's eventually happy about it.
- Morality Chain Beyond the Grave: Dr. Kroger talks about Trudy and wonders what she would think about what's happened to Monk under the cult's influence. When Monk still tries to brush it off, Dr. Kroger brings out a picture of her, says that it seems they can just discard it, and crumples it. Monk picks up the picture and begins crying.
- Outliving One's Offspring: Mr. and Mrs. Clark outlived their daughter, Amanda, who was murdered.
- Super Gullible: Stottlemeyer protests Monk's idea to go undercover with the Siblings of the Sun because of how gullible he is and how expert "Father" is at brainwashing people.