探案片《骑士的阴谋》是福尔摩斯前传。商人斯塔尔半夜被人杀死在回家的路上，为了破案，贝尔医生找到年轻的道尔协助他一起进行化验，捉拿凶手。在破案的过程中，他们发现斯塔尔在临死前曾向一位名叫阿丽西亚的女毛纺厂厂主逼债，导致这名妇女跳楼身亡。道尔他们认为一定是和阿丽西亚关系密切的人为了给她报仇才杀死了斯塔尔，并伪造成抢劫现场。很快，嫌疑犯被锁定在一个名叫涅尔本的商人身上。一切都可以让贝尔断定涅尔本就是杀死斯塔尔的凶手。但当警察前往涅尔本家时却发现涅尔本已被人杀死在路边，尽管大家已经看到了凶手，却还是没能把他抓住……

播出时间：2008年5月30日(星期五) 晚 10:30-0:30

When Sir John Starr complains that the investigation into his son's murder is not producing results, the Chief Constable asks Dr. Joseph Bell to assist. Bell agrees but there is some animosity with the officer in charge of the case, Lt. Blaney, as they had recently clashed on a different case. Bell enlist the help of Dr. Doyle who is in Edinburgh to visit his father. The younger Starr was a money lender and he had recently foreclosed on an account resulting in a young woman committing suicide. For the first time however, Bell and Doyle do not see eye to eye on the case and Doyle finds himself siding with Lt. Blaney. When a suspect is killed, Bell begins to question his own abilities and feels that his time may have passed.

10.30pm,30 May, ICS