Foolishly, you yearn for Patrick Melrose to be happy. By the close of Some Hope, the glimmer of redemption loomed in the dark by the lake. Thirteen years on, in Mother’s Milk, Patrick had indeed acquired the accoutrements of a contented life – wife, children, even a career. But alas, with the other hand the Lord taketh away.

An adaptation enfolding fidelity and freshness, Patrick Melrose (Sky Atlantic) continues to hover close to perfection. In this penultimate instalment, the fortysomething Patrick returned to the scene of his original sinning-against for a villa holiday. David Nicholls’s lithe script has never let us, or Patrick, lose sight of those formative nightmares, which loiter in flashbacks. But this time his tormentor was his mother (Jennifer Jason Leigh), now a Havishamesque crone enacting her own ancestral vengeance by tossing her son’s inheritance away on a coterie of New Age fruit loops corralled by the beaming cod-shaman Seamus (Jonjo O’Neill).

Patrick’s alcoholism (that mad dash for more whisky) looked much like his drug addiction – tragedy posing as demented farce. The glory of Benedict Cumberbatch’s performance is that he can pitch Patrick in each register: he is both seething, writhing victim and cruel, clownish destroyer. In another year, Hugh Grant’s Bafta for Jeremy Thorpe would be in the bag, but Cumberbatch is working on an even higher plane, towards a kind of three-way telepathy between character, actor and viewer.

Everyone else must dance around Cumberbatch but a richly watchable cast all seized their own moment in the sun. Celia Imrie had lashings of fun as the bullet-proof mother-in-law Kettle; ditto Blythe Danner as the ghastly aunt Nancy. But arresting on a deeper level was the laser-eyed sincerity of Anna Madeley as Mary, the wife at the end of her tether.

From the novel, which was nominated for the Booker Prize, I missed the section on the Côte in which Patrick reaches the calamitous understanding that he has become invisible to young women. But there were new compensations. The hiss of the cigar (which is not just a cigar). The camera atomising the Melrose family in the car by showing each in turn.

Director Edward Berger’s most eye-catching flourish was to follow Patrick and Robert (Marcus Smith) as they plunged clothed into the pool. It was as if Patrick sought a cleansing baptism for himself and his first-born, or perhaps a soothing return to the amniotic sack. No such luck: all it unleashed was a Munch-like scream of silent rage. Never was unhappiness so moreishly watchable.