After solving clues Takagi leaves suddenly and Conan reveals who the kidnapper is. Just then, the boy returns home unharmed, making them believe the culprit will try to make a run for it. After arriving to his house it is revealed that a winning lottery ticket was returned to the culprit in his mailbox, making him release his friends had no intention of stealing from him and the guilt of his crime caused him to suicide. Takagi manages to save his life while Sato yells at him for the danger he could have been in.

One day Mori Kogoro's private detective agency receives a blackmail call. It turns out that the caller has dialed the wrong number. Conan is able to identify the voice on the phone, it's similar to that of his old friend Heiji, who's also a high school detective but in Osaka. They join once again forces to solve the case and find the jewel which was stolen.

But they are not the only ones who are after the jewel. The notorious master thief Kaitou Kid has taken an interest in this piece, which is worth 100,000,000 Yen, as well and now it's up to Heiji and Conan to be the first to find the culprit and acquire the jewel.