《摩斯探长前传》第五季共6集，剧情以1968年为背景，于2018年2月在英国独立电视台播出。

　　Deputy Assistant Commissioner Charlie Hillian is killed on the night of his retirement party. Hillian was at one time a senior officer in Oxford and was in fact Morse's boss. He was also writing a book about his most memorable cases, including one about the unsolved death of an 8-year-old girl some 18 years ago. The suspect in that case, Frederick Redpath, was at Hillian's house the day he died and that chapter from the manuscript is missing. There are other suspects however, including Hillian's ghost writer who will now receive all of the book's royalties; a handyman who was working on the property; and Redpath's daughter, who knew the little girl who was killed all those years before. Morse comes into conflict with with a colleague DCI Dawson, who was one of Hillian's protégés, as they again look into the little girl's death.