Talented lawyer Kiyoshi Koshimizu (Sanma Akashiya) murders his girlfriend, Hinako Mukai (Naomi Akimoto), whom he won't break up with even though he has decided to marry someone else for convenience. Staging the scene as if her other boyfriend did it, Imaizumi is caught and arrested for Mukai's murder. Asking Koshimizu for help in his defense since they were former classmates, Koshimizu recommends Imaizumi plead to manslaughter to lighten the prison time. However, Furuhata is suspicious of Koshimizu's statements, and discovers evidence in the court records that may prove Imaizumi's innocence.
小清水潔（明石家さんま）はかつて古畑が犯人と突き止めた小石川ちなみの弁護も担当した敏腕弁護士。別の相手との政略結婚が決まったのに、別れてくれない恋人・向井ひな子（秋本奈緒美）を殺害した小清水は、犯行直後、ひな子の部屋を訪れた今泉にその罪を擦り付ける。逮捕された今泉は、真犯人とも知らず大学時代の同級生だった小清水に弁護を依頼するが、小清水は罪を軽くするため、傷害致死を認めるよう勧める。しかし、小清水の発言に不審を抱いていた古畑は法廷記録を読み返し、決定的な証拠を発見する。
