在东京都板桥区一间名叫“赤冢”的秘密侦探事务所里,有些好色的侦探“刺猬”七濑五郎(瑛太 饰),与搭档“老灰”木暮(森田刚 饰)接手各种委托,有时是令人感动的悲哀故事,有时是超乎想象的非自然事件。这天,他正在事务所楼下的小吃店和打工小妹萌美扯闲篇儿时,天花板突然发出奇怪的敲击声,那是所长风香露(山口智子 饰)发出的暗号,五郎急急忙忙返回事务所。这次找到侦探所的委托人是个叫川田的男人,他要求侦探们帮他寻找一个月前去世的女儿……Akatsuka Detective Agency stands inconspicuously at Shimo Akatsuka in Tokyo's Itabashi ward, right above a small snack shop run by their landlord. Akatsuka's eccentric chief Kaze Kaoru founded it with her two investigators Goro and Gure in order to take on odd cases that others are reluctant to do anything about. Their motto is "to be compassionate and meddlesome", which leads them to get involved in strange situations with their clients. Sometimes they're motivated by the potential to sell a sensational story to the press, but sometimes they end up working pro bono. They may be rough around the edges and always a little short on rent, but they always find a creative solution by diving into the mystery with their hearts even when they aren't sure if they'll succeed. They're joined by the Ranko, who first comes to them as a client, and other friends they meet along the way.