Last Bus to Woodstock

The fourth and final film of the season returns the series to its most dependable terrain: a woman dead in questionable circumstances, a set of respectable men with reasons to lie, and Morse's certainty that a death ruled an accident is in fact a cover for something uglier. Michael Wilcox wrote this adaptation, and Peter Duffell directs with a steady, mournful eye that lets the quiet horror of the case accumulate rather than announce itself.

Sylvia Kane, a secretary in her twenties, is discovered lifeless in the car park of a pub on the outskirts of Oxford, apparently run over. The scratches on her body suggest she was attacked before the wheels reached her, and Morse, John Thaw's sceptical inspector, treats the death as a killing from the first. In her handbag is an envelope addressed to a colleague, Jennifer Coleby, and the inspector reads in its contents a coded message and a large sum of money changing hands. A young man Sylvia had arranged to meet spends money far beyond his means and admits to taking cash and a necklace from her, yet Morse does not believe he is the killer; the boy's greed is real, but his nerve is not, and the careful work of a cover-up is beyond him.

The breakthrough comes from an elderly witness, Mrs Jarman, who saw Sylvia climb into a red car at a bus stop and later recalls the registration of a vehicle with a broken tail light. The car belongs to Margaret Crowther, wife of Bernard Crowther, an Oxford don played by Anthony Bate with the flushed, entitled manner of a man who believes the world arranged for his convenience. Crowther admits giving the girl a lift, stopping for a drink, and rejecting her advances, and he recalls reversing with a slight bump he assumed was a kerb. His wife, though, fights any confession: her husband is in the running for a professorship, and the scandal would destroy him and the comfortable life they have built.

The episode's quiet power lies in its portrait of a marriage defending itself with lies. Ingrid Lacey's Mary Widdowson, Jill Baker's Jennifer Coleby, and Holly Aird's Angie Hartman supply the supporting texture of working women who see more than the men around them credit. As Crowther sets about disposing of evidence, the strain tells on his heart, and the investigation tips from puzzle into human tragedy. Morse, as ever, is less interested in the letter of the law than in the truth of what happened on that dark stretch of tarmac, and the season ends not with a flourish but with the familiar, depressing recognition that the people most capable of murder are often the ones society is least equipped to suspect.