Natsumi Yukihira (Ryoko Shinohara) receives secret documents of an organization that controls the country from the shadows. Because of this, Natsumi's ex-husband, Kazuo Sato (Teruyuki Kagawa) pays a terrible price. Natsumi goes back to the Investigation #1 of Tokyo Metropolitan Police Department to take on the organization, but Natsumi becomes involved in a new case. She gets closer to the final enemy.

After detective Natsumi Yukihira brings an end to the police hospital terrorist case, Natsumi is transferred to the Nishimonbetsu Police Station in Hokkaido. Meanwhile, a series of grotesque murders occurs in downtown Tokyo involving nails placed in the body of the victims. The fingerprint of Natsumi's ex-husband, freelancer journalist Kazuo Sato, is found on the the body of a victim and Kazuo is placed on the most wanted list. Soon after, Kazuo finds Natsumi and hands her a USB memory stick. The device contains information on a secret organization within the police department. Kazuo tells Natsumi that the series of murders are warnings and suspects become the next victims. Natsumi is then arrested as a suspect. Tokyo prosecutor Katsuaki Murakami appears at the Nishimonbetsu Police Station to investigate.

居住在某富人社区的望月夫妇过着令人欣羡的幸福生活。望月幸平（伊藤英明 饰）出身贫寒，不过他的妻子真理亚（木村佳乃 饰）家境优渥。真理亚的父母去世后留下了丰厚的遗产，利用这笔钱幸平经营了一家咖啡店。日常里幸平的衣食起居全由真理亚一人照顾，妻子体贴入微，甚至连望月老家的母亲和姐姐也都关爱有加。可就是这样一位近乎完美的妻子，却因无微不至的关怀而引来幸平越来越多的反感。他与咖啡店主厨北里杏男（相武纱季 饰）陷入不伦之恋，后者则怂恿他杀掉妻子。
就当计划准备实施当天，妻子疑似遭人绑架。对方索要两亿日元赎金，否则将杀掉真理亚。看似老天帮助了幸平，然而接下来的事实却让他惊恐万分……

相河一辉（高桥一生饰）在大学教授研究动物行为的“动物行为学”，半年前刚开始讲师的生活，但是他太喜欢各种生物，沉迷于研究，甚至不遵守大学的规则，每天都在职场挨批，而且他不太遵守时间，还被牙医吐槽没常识。一辉非常诚实，有时对学生的提问直接回答不知道，让学生困惑，他坚持兴趣，不守固定观念的样子也影响了身边人的价值观。