The Butt Detective solves crimes by literally detecting butts. That's the entire premise, delivered with zero irony or winking at the camera. This movie commits so completely to its absurd central conceit that the mystery plot becomes secondary to watching a children's show operate with the deadpan confidence of a noir detective thriller.
A missing contestant at an idol competition sends Butt Detective undercover to Stardust Island, where glittering stages hide something far more sinister. The island serves as headquarters for Phantom Thief Academy, a criminal organization orchestrating a dangerous scheme called the Dark Age Plan. Disguised as a contest hopeful, Butt Detective navigates both the competition and the criminal underworld, piecing together clues while staying undetected. Things get complicated when Phantom Thief U crashes into the investigation with their own agenda: stealing the Moonlight Stone from the organization's leader, Phantom Thief G. Unlikely allies become necessary as Butt Detective realizes the missing person case connects to something much larger than a single disappearance. The adventure also peels back layers of Brown's mysterious history, revealing secrets that reshape what the detective thought they knew. Expect mystery and comedy colliding in a world where idol dreams and criminal conspiracies occupy the same space, where nothing on Stardust Island is quite what it seems.