You arrive at a resort mystery where the victim's death matters less than everyone's lie about why they're there. Kindaichi walks into a locked room full of secrets, but the real trap is that the killers and their target are already inside with him, none of them knowing which face in the crowd is the one they came to murder. By the time the body drops, you're already three layers deep in motive, and the movie never lets you surface long enough to catch your breath.

Kindaichi, Miyuki and Fumi are invited to the Deep Blue Island resort by their senpai Akane, whose father heads the Aizawa Group. The trip takes a dark turn when a band of criminals slips into the hotel disguised as waiters, planning to kill the Aizawa Group members. Yet the killers work with a serious blind spot: they have never met their boss face to face, and they do not realize he is staying at the hotel alongside the very people they came to murder. The film is a mystery that retells the Deep Blue Island arc of the 1997 Kindaichi TV series in an alternate form.