Arlene

The title gives the case its face: Arlene. A vulnerable young woman needs help, and Inspector Jean Darblay decides, early and firmly, that helping her is the job. The episode is not really about crime at all, or rather it is about the kind of crime that never shows up in a charge sheet until someone decides to notice it.

Arlene Davis, played by Amanda York, is the sort of person the system keeps losing track of, and the episode follows Darblay's attempts to get a grip on her situation before it tightens around her. The work is patient and frustrating in equal measure. Sergeant Joseph Beck and Sergeant George Parrish support the effort, PC David Gallagher runs the messages, and Detective Chief Inspector Jim Logan supplies the institutional muscle when it is needed. Around the edges move the people of Arlene's world: Deano Forbes, Bobby Dawson, Roy Brown, and Muriel Davis, played by Patsy Rowlands, a face Carry On fans will recognise, bringing her usual warmth to a part with more weight than her comedy roles ever gave her.

Brian Finch wrote it, Les Chatfield directed. Stephanie Turner is Jean Darblay, with David Ellison as Beck, Noel Collins as Parrish, Tony Caunter as Logan and Gerard Kelly as Gallagher. Amanda York is Arlene Davis, Max Hafler is Deano Forbes, Paul Humpoletz is Bobby Dawson, Michael Deeks is Roy Brown and Patsy Rowlands is Muriel Davis.

The episode's heart is the simple act of one woman refusing to look away from another. There is no glamour in it, no clever twist, just the unglamorous labour of intervention: phone calls, home visits, and the steady pressure of someone official actually caring. The show was always good at this register, at turning the quiet parts of police work into drama.

It is the kind of hour that reminds you why the series mattered. Protection is most of the job, and it does not always wear a uniform.