Shipton Abbott continues to keep DI Humphrey Goodman and his team busy, with a baffling new crime each episode. From a death on a steam train to a missing teacher, the team have their work cut out. Even more so with Police HQ’s threat of the local station house closure hanging over them – the pressure is on to get results.　　Meanwhile, Humphrey and Martha’s journey to find their own version of a family continues as they explore the possibility of fostering. Martha’s mother Anne throws herself into the world of online dating, and a well-meant gesture from Esther’s daughter Zoe threatens to uncover a long-held secret…

“上世纪90年代初，正值国际禁毒战争的高峰期，负责英国边境事务的政府机构——英国皇家海关总署意识到，他们在打击毒品走私的战斗中节节败退。他们的解决方案非同寻常，”剧情简介写道。“在一项绝密行动中，一支由英国海关雇员组成的小队被派往英国最危险的贩毒团伙内部执行卧底任务。”“他们并非训练有素的间谍。这些人都是来自英国各地普通民众的普通男女，经过基础训练后，被要求在犯罪世界中建立新的身份。这些身份被称为‘传奇人物’。”

希普顿·阿博特继续让警探汉弗莱·古德曼和他的团队忙个不停，每一集都有一桩令人费解的新犯罪。从蒸汽火车上的死亡到老师失踪，团队的工作都十分繁重。更重要的是，警察总部威胁关闭当地警察局，他们面临着取得成果的压力。与此同时，汉弗莱和玛莎继续寻找自己的家庭，他们探索收养的可能性。玛莎的母亲安妮投身于网上约会的世界，而埃丝特的女儿佐伊的善意举动可能会揭开一个长期隐藏的秘密……