[When Erika rejoins him, she's carrying a knife which she flips with ease. Then she holds it out to him and produces a second one for herself.]

Mikado? I have a new theory. This has happened to me before. It's not a fair trick. But it really gets me going that I can finally seal that closed room! The detective always catches the culprit. We just have to stop them from entering another room while we're checking again.