Kogoro, Conan, and Ran's rental car runs out of gas, so they have college student Saeki tow them to a nearby supermarket with his van. Saeki and his classmates Haruka and Tamada leave their drunk professor Goto in the back stea while they go shopping. Later, the students discover Goto dead inside the car. Goto wore his cell phone on a strap around his neck, which strangled him when he slid down in his seat. Inspector Megure believes it was an accident, but Conan finds something strange about the case...

Mitsuhiko, Genta, Ayumi, and Haibara discover the body of serial blackmailer KUMO at a construction site. Conan is visiting the hot springs with Kogoro and learns about the case when Mitsuhiko contacts him. The Detective Boys witnessed a tall man fleeing the crime scene around the time the murder took place. The police believe KUMO was blackmailing ten men and one woman. However, all 11 of them have alibis, and the investigation comes to a standstill. When Conan hears about the situation, he notices a few inconsistencies...