While Ran, Sonoko, and Conan go to a coffee shop after getting a popular concert ticket, another customer arrives with her friend and loses her ticket there. The next day, she comes back showing the same ticket auctioned off on the internet. While the three along with the manager, another employee, and the customer go to the home of another employee who hadn't arrived to work, they find her dead. The house appears to have been robbed. Another tenant explains that she went to a convenience store after putting some clothes to wash in the machine. He observed this because it was emitting a different, loud noise. He also tells that there was a 5-minute pause in between. Conan, through a sleeping Sonoko, deduces that the employee is the murderer. She took the ticket but the aprons between them got exchanged. And while she was trying to get the apron out of the washing machine, the other employee returned. She accidentally causes her death and stages a robbery.