House Calls

Children in Denton are being injected with water by a stranger breaking into their homes, and the pattern takes Frost straight back to Sydney Snell, a man with learning disabilities he sent to prison years earlier on a promise of psychiatric care that never arrived. Snell, released, is convinced he is helping the children — the injections, in his mind, are medicine. Frost, weighted down by guilt over the broken promise, lets him go.

The decision nearly ends him. DS Liz Maud, appalled by his leniency, reports him for neglect of duty. Then a carpet fitter Mark Grover comes home to find his two babies dead and his wife gone — the infants were injected with water after they died, and suddenly Snell is the prime suspect in a quadruple tragedy. DCI Peters assumes the case; Mullett warns Frost of an inquiry; Snell confesses to the injections but insists the children were already dead by the time he found them.

Frost, who trusts his instincts over confessions, keeps digging. Nancy Grover's body is found in a railway tunnel — a staged suicide, the coroner rules, until stab wounds say otherwise. And then the truth arrives in pieces: Nancy had tried to obtain an abortion and was refused on mental-health grounds; Mark's alibi collapses when Frost learns he was let off the Bonley's premises with leftover carpet remnants. Confronted, Mark confesses the whole miserable sequence: he and Nancy argued, and Nancy, crushed by depression and the impossible strain of family life — smothered their children herself. Mark killed her in a rage, and his friend Phil Collard helped dispose of the body. The children's deaths were not Snell's crime; he only found them afterwards, and his terrible kindness was to try to help them anyway.

House Calls, written by Malcolm Bradbury and directed by Graham Theakston, is the series' most compassionate and most uncomfortable episode — a study in how the system keeps failing the vulnerable, and how a detective's mercy can look exactly like negligence. Maud, who reports Frost and then apologises before transferring away, is the episode's conscience; Frost, who trusted a broken man because he broke him, is its wound.

The most uncomfortable episode the series ever made — a study in mercy and its costs, with a confession that refuses to let the viewer off the hook. Uncomfortable and compassionate in equal measure.