Saya Toma is a female detective with an IQ of 201. Takeru Sebumi is a career detective with a distinguished background. They work on cases by postulating the "SPEC" of the unknown criminals and then deduce the criminal's unknown "SPEC" to make arrests. A mystery occurs when bodies are found on a cruiser in the ocean. Saya Toma and Ryo Kase of the Tokyo Metropolitan Police Department are brought in to solve the case.

Graduating at the top of her class, elite detective candidate Jun Shibata is transferred to the section that handles cases deemed "unsolvable" by the department. Her partner, though a well-respected and experienced detective, has grown complacent after unsuccesfully pursuing these cases that many consider an exercise in futility. With her upper class breeding, her colleagues don't expect much from her either, but she suprises them all with her motivation and astounding powers of deduction. Well-constructed mysteries and colorful characters abound in this stylish and edgy police drama.

在事件搜查中接受枪弹陷入为昏睡状态的纯8个月后总算醒了。因为一时心脏停止脑有障碍，丢失了作为警官的记忆。
真山从朝仓那儿接到在人山人海的街中，「再开始游戏」的消息。另一方面，恢复的纯在八王子西署就任署长，在派出所首次上班途中遇到女子高中生Misaki说「诅咒的树杀死了人的」。据说伏船神社的神树雕刻“想杀的人的名字”的话那个人物有在7日以内死这样的传言，Misaki写原恋人钱的名字，结果他真的因事故死亡了。很有兴趣的纯立刻在神社神树上刻上了名字，对被刻上名字的人开始搜查......
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搜查二系是警视厅里备受冷落的所在，虽说顶着“专门负责处理久而未决的案件”的头衔，其实部门里的人都在混日子。直到有一天，东大高材生柴田纯（中谷美纪饰）加入，柴田纯具有罕见的运算和分析能力，破案的过程可谓惊心动魄，但另一方面，她是个非常单纯的生活白痴，同事真山彻（渡部笃郎饰）是她的拍档兼保姆，照顾着脱线的柴田。
真山的身上背负着一个沉重的过去，7年前，妹妹被轮暴，可是凶手始终没抓到，柴田开始重新调查这一事件，却发现过去的种种混杂交织在一起，怎么也拨不开这层迷雾……