Truelove review: With the spirit of a police procedural, this isn’t your typically mawkish euthanasia drama

Lindsay Duncan and Clarke Peters star in this twisty thriller exploring the ethics of assisted dying

Resolve is a luxury of the year’s early months and our still attainable resolutions. But how do we stick with a promise when it becomes harder to keep, more unfathomable to fulfil? This is the question faced by a group of elderly friends in Channel 4’s mercurial new mercy-killing drama, Truelove.

Attending the funeral of a mutual friend, old flames Phil (Lindsay Duncan) and Ken (Clarke Peters) find themselves reconnecting after decades apart. He’s spent a career in the shadowy world of the military, while she’s retired following a successful stint in the police force. Over drinks at the pub alongside a few old muckers, the group find themselves drawn into a strange pact. “If I get anywhere near that, take me out the back and shoot me,” Phil says of the deceased who had fought debilitating cancer. And that’s just what they agree to do: “true love” becomes their codename for a shared, half-joking obligation to put one another out of their misery. “Ken can bump us off,” says ex-doctor David (Peter Egan), “and Phil can cover it.” The perfect crime.

From then on, it is a case of Chekhov’s suicide pact. One by one, the signatories of the pub agreement find themselves beset by ailments. First up is Tom (Hot Fuzz’s Karl Johnson) who finds himself battling the “full English” of cancer diagnoses. But what friend would possibly risk their life and liberty to fulfil a drunken, semi-bantering promise? This is the question explored over four episodes by writers Iain Wetherby and Charlie Covell (no stranger to pitch-black scenarios after co-writing The End of the F***ingWorld). It’s a premise that laces the potential mawkishness of a euthanasia drama with the spirit of a police procedural – and the twist of a serial killer saga.

At Truelove’s heart is Lindsay Duncan, who is on imperious form as a retired copper with little left to lose. She enters proceedings in a black convertible, puffing on a cigarette and wearing dark sunglasses – a long way from The Best Exotic Marigold Hotel or any other fuddy-duddy depictions of older life. In the absence of a manufacturing industry or any natural resources, Britain’s greatest export may well be its older female actors. And Duncan is a consistently underrated part of that output. She is harder than Judi Dench, colder than Penelope Wilton, more taciturn than Maggie Smith, with the flawless ability to move between brittle and steely modes. Next to her, Peters – a veteran American actor, best known for The Wire – feels necessarily diminished.

That said, there is something a bit weird about Truelove’s premise. Last festive season, we were treated to a BBC adaptation of Andrew O’Hagan’s novel Mayflies, about a friendship that ends with a trip to Switzerland for an assisted suicide. Where that was an emotionally brutal but deeply conventional look at end-of-life care, Truelove is far pulpier and commensurately less affecting. The tonal shift between the first episode’s opening act and its closing one will leave some viewers with whiplash. As the series progresses, the role of a young police officer, played by Scottish actor Kiran Sonia Sawar, becomes more important, and the question changes from whether you should offer a painless death to someone begging for help, to whether you can get away with it if you do.

Still, with its excellent cast and unusual, if scattershot, tone, Truelove has a lot more to say than most of the limited-series dramas we were served over Christmas. On the subject of ageing, it is unsentimental in a way that few shows are. “Everybody knows it goes,” Phil tells her husband (Phil Davis), counting off the stages of geriatric life. “Bungalow, hospice, crematorium.” When she visits the dreaded bungalow of an old friend, he warns her against downsizing. “You start moving into smaller and smaller boxes,” he says. “Soon they’ll be measuring you up for your wooden overcoat.” Whether it is surreptitious fags in the garden, half-cut flirtations, or embarking on a spree of mercy killings, Truelove is about raging, not going gently, into that good night.