Lewis returns to Oxford after several years absence and is reluctantly assigned by his new boss, DCS Innocent, to the murder of an Oxford mathematics student who was shot while participating in a sleep study. The key-code used to access the sleep lab was assigned to a fellow maths student, Daniel Griffin, but Daniel&♯39;s math tutor has provided him with an alibi. Daniel is a maladjusted young man who will soon inherit his father&♯39;s automotive empire. He is disruptive and has no respect for his uncle who now heads the company. The future of the company however rests on an impending deal with Japanese investors who insist that family unity is all important at this time. When two other murder occurs, Lewis must decipher a cryptic clue left in an old case file by his former boss, Chief Inspector Morse.

　　该剧围绕两名新手侦探展开，他们被派往充满神秘色彩的峰区地区进行调查：刚搬到该地区的戴安娜·弗莱，以及在这个小村庄里生活了一辈子的本·库珀。

　　特雷弗·宾利（罗温·艾金森 饰）上次在《人来蜂》中照看高科技宅邸，却因为恼人的虫横加捣乱，酿成巨大灾难，这次离开了帮人看家的高压世界来担任学校工友，享受安静一些的生活。此时出现一个高薪工作机会，要他在圣诞期间到奢华伦敦顶楼公寓顾家，这样的诱惑实在令人难以抗拒。没想到学期的最后一天，居然没人来接学校圣诞剧的耶稣宝宝，特雷弗多了一位出乎意料的小同伴。这下他得照看顶楼公寓，还得照顾小宝宝，特雷弗还能享受他期待的平静圣诞吗？又或者这个佳节会就此陷入大乱？

　　牛津市郊一处房屋发生爆炸，一名女孩在爆炸后失踪，她的邻居莎拉·塔克（露丝·威尔森 Ruth Wilson 饰）一心想找到女孩，并寻求私家侦探佐伊·波姆（艾玛·汤普森 Emma Thompson 饰）的帮助，两人突然发现自己卷入了一场复杂的阴谋。