改編自橫溝正史推理大獎優秀獎作品

佐佐木任職於地方市政府的社會福祉事務所，以社會個案工作員的身分負責弱勢生活補助者的評估以及後續相關的訪視與協助。在某個正忙於與棘手的受補助者周旋的炎夏之日，佐佐木在偶然的情況下得知了同事用中斷補助要脅、逼迫負責的個案女性以金錢與身體來換取補助資格的延續。為了確認是否真有其事，佐佐木與同僚造訪了個案林野愛美的家，沒想到威脅事件竟然逐漸朝著令人意外的方向發展。於社會底層奮力掙扎的人們，一個、一個被捲進了黑暗的漩渦……。

Mamoru Sasaki, a welfare caseworker, discovers that his colleague is taking advantage of his position to have physical relationship with a female welfare recipient. To verify the truth, he visits the woman's home and unexpectedly falls in love with her, which leads him to be involved in a conspiracy by the Yakuza.