故事以加藤实秋的小说「Maison De Police」系列为原型，描绘了主人公新进刑警牧野ひより（高畑）来到了只有退休警察居住的共享房屋「Maison De Police」，被一群能力超群知识丰富前警察“大叔”们呼来喝去的同时，解决了一个又一个案件的故事。

Prosecutor Kohei Kuryu takes charge of a case with a foreign embassy possessing the key to solve the case. Due to the extraterritoriality involving the case, the investigation has not gone anywhere. A crisis then ensues. Kohei Kuryu and his office attempt to extract the truth behind the wall of the Neustrian Embassy.

Kuryu Kohei returns to Tokyo Prosecutor's Office once again. There are familiar faces, but also new faces who will be working with him this time round. One of them is paralegal, Asagi Chika, who is now in charge of going along with Kuryu's whims.