While Kogoro, Ran, and Conan are driving near the ocean, their car breaks down, prompting them to ask for help at a house which belongs to famous lawyer Kensuke Tachibana. There, they meet secretary Yuuichi Sakuraba, his caretaker Yaeko Kamei, his wife Yuki Tachibana, his office's accountant Noriko Sugimura, and lawyer Fumio Fujisawa. As the day progresses, Kensuke explains to Kogoro that he’s been receiving threatening letters from someone with the initials “T.K.”