This one works on you because it puts Haibara alone with her own paranoia and takes Conan out of the country. Twenty-odd minutes, no Kogoro, no Mouri agency, just Ai and Ayumi killing an afternoon while Conan and the others are off in London, and a cluster of grim-faced strangers turning up where they shouldn't be. For a character who reads every stranger as a possible Black Organization tail, that setup does more damage than a body in a locked room. Ayumi is the whole counterweight: she has no idea what Ai is actually afraid of, and she sticks around anyway. It is a bonus OVA bundled with the manga, so it never pretends to be a landmark case, but it understands that the scariest thing in Detective Conan is Haibara with time to think. Fans of hers will clock it instantly.

Diana invites Kogoro and Ran to London. Conan cannot make the trip under his made-up identity, so Ai gives him a temporary antidote that lets him go as Shinichi Kudo, and he boards the plane with them and Professor Agasa. Back in Japan, Ai is living with Ayumi, and a shady figure dressed in black named Yoji Kurokawa has been hunting for her and finally locates her near their apartment. Mitsuhiko spots a magazine photo of Grace Aihara, a foreign actress who is Ai's double, and soon after Conan phones with an ominous request to keep Ai away from the Professor's house. Mitsuhiko and Genta then set out to protect her in this Detective Conan OVA that mixes mystery, adventure and comedy.