KEY POINTS:
In last night's Prime Suspect: The Final Act (TV One, 8.30), Detective Superintendent Jane Tennison takes her young friend Penny to see a painting. Penny, whose 14-year-old schoolmate has just been murdered, thinks the tiny, doe-eyed child in Joshua Reynolds' Strawberry Girl looks afraid.
The policewoman sees curiosity and anticipation as well as fear in the intriguing mix of emotions on the child's face. "I wonder what's in store for her?" she says.
Whatever the answer, you can see her thinking, it's bound to include regrets. The nearly 60-year-old Tennison has more than a few of those herself, and they suffuse this improbably compelling final instalment to a crime series which is now more than 15 years old.
Revisits to television drama greats of yesteryear are potentially fraught with disappointment, as that recent mediocre Cracker reprise showed.
Jane Tennison, too, was so much a character of her time, a lone female boss in a gritty urban cop drama, fighting sexist put-downs and as ambitious as the men. Now, when the box is littered with female detectives who crack their cases and have sizzling private lives, too, surely the once pioneering Tennison is nothing more than a sad, old anachronism.
In Prime Suspect the Final Act, we meet Tennison on the verge of retirement and a full-blown alcoholic.
The opening scenes say it all: she wakes after having passed out on the couch, the phone is off the hook and she can't remember the call or how she got that bruise on her face, then it's off to the kitchen for a vodka breakfast.
But the old Jane, determined as ever to get her man, hasn't disappeared. The drama succeeds in capturing something more complex than the cliche that women who put their careers over personal lives come up empty-handed.
Life is coming full circle for Jane but not in quite the way we expect. There is the possibility of redemption in unlikely ways. And if she's being punished for her choices, then those who've led more conventional lives are shown to be suffering, too.
Out on the streets, meanwhile, a schoolgirl has been murdered and we are back on familiar Prime Suspect territory of sleaze, corruption and benighted lives in the underside of modern Britain. But the whodunit is just the framework.
The most nail-biting element is whether Tennison will survive what her life has become, a cliff-edge walk in the dark, as she tries so desperately to dispel the guilt and loneliness and go out on a win.
Oscar winner Helen Mirren, in a year of queenly triumphs, confirms the unglamorous, difficult detective as her greatest role. Her face is mesmerising: as bleak and blighted as the urban wastelands she's trawling through to find the killer, then suddenly alive with intelligence, resolve and that always surprising level of compassion.
Mirren invests Tennison's usual head girl demeanour with the slow deliberation of the imploding alcoholic determined to convey sobriety to a watching world. It's a high wire act.
Her performance is backed by a superb supporting cast: Tom Bell comes back as Bill Otley, an unlikely saving angel with a face like Edvard Munch's The Scream. Laura Greenwood's Penny is an utterly convincing mix of artlessness and deception. Katy Murphy and Gary Lewis are the murdered girl's parents and gut-wrenching in their pathos, anger and denial. Lewis, in particular, is almost too painful to watch as he constantly tears up the set, a one-man cluster bomb of rage.
The result is a series of heart-stopping moments, from Penny's poetic eulogy at the funeral, to the lines of the police search advancing like an army over the blasted heath and that moment in the interrogation room when the suspect alerts everyone to the fact that his inquisitor reeks of drink.
At the end of two hours, you realise this was the rarest of viewing experiences. Despair takes hold that it's a whole seven days until the concluding episode. It will be a very long week.
