Sonoko writes a murder mystery and immediately gets roasted by Haibara for bad deduction logic. What starts as a meta joke about Case Closed's own case construction becomes genuinely funny because the show knows exactly how ridiculous detective anime plotting can be. You're not watching a mystery unfold, you're watching the cast tear apart bad mystery writing, which is somehow more entertaining than an actual case would be.

Sonoko sits down to write a mystery play script for a charity event, putting a high school detective named Suzuki Sonoko at the center of a murder case. The script is unfinished, though, and she has no idea who the killer is or why the crime happened. With the play only a week away, it has to be done today. When Haibara reads through the draft, she spots serious flaws in the chain of deductions. Ran first turns to Kogorou, whose idea turns out to be the same one Sonoko already used, so she calls Shinichi for help instead, while the Detective Boys pitch in too. The result is a single mystery OVA built around fixing a fictional case.