Will’s life has changed for the better. He is happily married to the brilliant, Bonnie and due to become a father but his world is about to be rocked by a terrible accident.
　　He’s always preached the word of a compassionate God – but how can he now, when his despair leads him on a dangerous downward spiral. Geordie has found a new contentment in his relationship with Cathy but when they are both confronted with shock announcements at work their new-found happiness is threatened. As Mrs C, Leonard, Jack and Daniel rally around, both Will and Geordie find themselves in unfamiliar, emotional waters and murder is always around the corner.
　　Series eight of Grantchester will range from speedway to spies, exploring the lives of invisible women and the very visible problems caused by Leonard’s new vocation which may, once again, find him battling the law. Exploring faith, forgiveness, and redemption – this explosive series of Grantchester tests Will and Geordie to the limit.

故事讲述两个在当代具有超自然能力的人“乔治”和“米歇尔”。在当地一个不知名的医院里做苦工，他们生活绝望-因为米歇尔是吸血鬼，乔治是狼人。他们决定改过自新，住在了一起才发现，一个女鬼(Annie)死于神秘的情况并且经常闹鬼。在这个一个对两个人的竞赛中(Threesome 有三人一组或者一人对抗两人的意思，这里应该指安妮女鬼和乔治米歇尔搭档)，他们与超自然生物对抗，希望通过这样的生活方式与他们的邻居-人类相处。

故事从两个不同寻常的“人类”开始，分别叫做George和Mitchell，他们一个是吸血鬼，一个是狼人，在当地一个不知名的医院里做苦工，他们生活绝望——因为mitchell是吸血鬼，George是狼人。他们决定改过自新，同住在了一起才发现，一个女鬼(Annie)死于神秘的情况并且经常闹鬼。不仅这样，Mitchell认识的几个吸血鬼和Mitchell不同，他们都对人类没有任何怜悯之心，而Mitchell不想这样，于是争端渐起。
　　三个非人住在一起，打算和人类和平共处，表现得更像是个人类，他们在这条看似不可能的路上到底要怎么走下去？让我们跟随三人的故事一同打开这个神秘世界的大门，通过他们看看我们的世界。

Section 20 are called into Bangkok, Thailand to rescue Chloe Foster, the daughter to British ambassador and longtim friend of Phillip Locke (Green), Robin Foster (Tim McInnerny). The team find the compound where she is being held, but during the raid the kidnappers escape with Chloe. After identifying the lead kidnapper as Ray McQueen (Max Beesley), Michael Stonebridge (Winchester), Damien Scott (Stapleton) and Julia Richmond (Lukes) track him to a nightclub and plant a tracker on him. However, McQueen soon realises he is being tailed and tries to escape with Chloe again, while also contacting Foster to deliver an armed bomb to the embassy where he is negoatiating with the North Koreans. With less than fifteen minutes, Scott and Stonebridge have to find McQueen and contend with a local gang. They ultimately rescue Chloe and apprehend McQueen, but Locke fails to stop Foster before the bomb detonated, killing Foster and a North Korean general

在享受一个难得的假期之后，Scott（Sullivan Stapleton）和Stonebridge（Philip Winchester）被召回20分部接受新的任务。另一名20分部特工在黎巴嫩贝鲁特追踪高深莫测的恐怖分子al-Zuhari不幸丧命，Scott和Stonebridge必须查清事情的真相。一条新线索引导他们来到哥伦比亚的偏僻丛林——拒信al-Zuhari的一个盟友正潜藏在这片由势力庞大的贩毒集团控制的地区。
　　Rhona Mitra将继续在本季扮演Rachel Dalton少校，Michelle Lukes扮演Julia Richmond中士，Liam Garrigan扮演Liam Baxter中士。
　　本季新加盟的演员包括：Robson Green扮演Philip Locke上校；Dougray Scott扮演叛逆特工James Leatherby；Milauna Jackson扮演反恐行动组在执行任务过程中遇到的关键人物Kim Martinez；Zubin Varla扮演神秘的可疑对象Leo Kamali。