Felix McClure, an Oxford University professor, is stabbed to death in his college study. Not only was he an expert in his field but he was one of the University's key fund-raisers. The investigation focuses on Brooks, a one-time cleaner for McClure who quit his college job abruptly after a student, Mathew Rodway, jumped out of a college window high on drugs. When Morse learns that Brooks' daughter was the object of affection for both Rodway and another student, he has another possible suspect. Brooks' wife also worked for one of McClure's friends and Morse uncovers a conspiracy that he may not be able to prove
女教师斯蒂文斯患脑癌即将离世，她的清洁工布兰达知道后伤心不已，女教师说死没什么，重要的是生前要留下些什么，预示后面的献身。
布兰达的保安老公在大学里出售毒品，曾导致学生磕药后跳楼自杀，后被教授发现后还用在学校文物柜顺来的刀将教授杀害，回家后计划将凶器放回，可不巧老公心脏病突发，布兰达为善后，处理带血的刀、丢弃作案时的衣物等，可是换来的却是一次次的家暴，还被打伤。教授的女友刚好是布拉达的女儿凯。此时女教师的杀人计划已经开始。
斯蒂文斯色诱其学生凯文打破展览馆的文物柜，制造杀人凶器才被偷的假象以及众人的不在场证明，误导警方调查，实则在此之前布兰达母女和斯蒂文斯三人合伙已杀死布兰达丈夫，深夜开车抛尸河中，最后女教师死前留下遗书，承认都是她一人所为，Morse也无法证明另外两人也参与其中，案件只能结束。