Appendix Man

Months after his resignation, Frost is back — not working, exactly, but parked on extended compassionate leave by Mullett, who is chasing the Assistant Chief Constable's job and cannot afford the optics of losing his most famous detective. But the press are sniffing around an old case: the Black Farm Murders, which carried an unsolved theft of precious paintings; Frost concludes the man claiming responsibility is just seeking attention. Then Hazel Wallace, promoted to Detective Sergeant, returns to Denton and finds a body that will not stay simple.

Lester Bryce-Jones, an art collector, is found hanged at home — a suicide, Wallace suspects, until a Hockney painting from the Black Farm haul turns up stolen from his flat, along with fingerprints matching the Appendix Man: the unidentified body pulled from a river a year earlier, whose case has haunted Frost since the third season's Dead Male One.

The unravelling is baroque. Bryce-Jones wore several names and earned his keep as a lowly hospital porter while quietly selling expensive paintings. His neighbour Debbie Viner helped him sell them for money, then found him barely conscious after a dangerous sexual game with drink and painkillers — and let him die, taking the painting, which turned out to be a forgery. The Appendix Man's fingerprints, Frost discovers, were tampered with; they belong to Diana, a pathology lab assistant whose brother David was being blackmailed by the dead man, a thief named Ian Priest. Priest had come into the stolen Black Farm paintings but, hospitalised with appendicitis and terrified of being linked to the case, was helped out of the hospital by Bryce-Jones — who, when Priest collapsed, pitched him from a bridge into the river.

The case is a magnificent puzzle-box, and the episode's quiet engine is the reunion of Frost and Wallace, the WPC who has grown into a detective in her own right. Mullett, meanwhile, misses the promotion — senior officers notice that Frost signed his own expense forms, which Mullett had unknowingly approved; Frost offers his resignation again; Mullett, once more, declines. Appendix Man, written by Malcolm Bradbury and directed by Sandy Johnson, closes the loop on the series' most patient mystery, and lets its hero come home at last — the marital house finally repaired, the lonely detective moving back in.

A magnificent puzzle-box of a mystery that finally closes the Appendix Man thread — and a quiet homecoming for the loneliest detective on television. A puzzle-box resolved at last, and a hero finally home.