The Last Weekend, ITV1

Although you probably wouldn't want to cast Rupert Penry-Jones as Falstaff or Arthur Daley, point him in the direction of a privileged and successful London barrister and you can't miss. In this three-part adaptation of Blake Morrison's novel, Penry-Jones is instantly in his element as Ollie, metropolitan legal eagle and partner of the glamorous Daisy (Genevieve O'Reilly), a professional head-hunter.

However, all is not as it seems, as his old college friend Ian (Shaun Evans ) and his wife Em (Claire Keelan) begin to discover when they join the gilded couple for a weekend in an old house in the Suffolk countryside. "Male jealousy" is said to be the driving theme of The Last Weekend, and it's going to take a variety of forms. 

We got an early heads-up from Ian, who appears in two overlapping time schemes. He's one of the protagonists in the unfolding drama, but he also makes regular interventions as the narrator of the story, looking back on it three months afterwards. Frightfully postmodern, but in this case it works quite well. Evans plays Ian-the-commentator with an ambiguous mixture of matiness and evasiveness, so you can never quite trust what he's telling you. Anyway, one thing he has told us is that he and Daisy had a bit of a thing before she got together with Ollie, and what's more she called him before the trip to Suffolk to say she had something to tell him (Claire Keelan and Genevieve O'Reilly, pictured above).

Thus, the reunion of Ollie and Ian is fraught with undercurrents from the beginning, despite the jokey set-up of Ian and Em being interrupted by the arrival of the RAC's breakdown van just as they were manoeuvring into position for a quick bonk in the front seat of their elderly Fiesta. When they finally reach the weekend house, Ollie greets them with exuberance and champagne, while a skimpily-clad Daisy hopes the more modest Em will join her in some topless sunbathing. Then Ollie suddenly invites Ian for a game of golf, in an imperious tone which doesn't leave much room for refusal.

The game re-lights the fuse on the pair's long-standing rivalry, which stretches back to when they were both law students, and suddenly a "friendly" nine holes finds them wagering a grand on the outcome. Not that Ian was as unprepared as he seemed, as we learn from a flashback of him diligently practising his golf drives. And it won't be just one game - it turns out they have a history of ultra-competitive triathlons, and this looks like turning into another (the boys go golfing, below).

From the start we've sensed Ian's discomfort at the disparity between his own modest lifestyle and Ollie's ostentatious achievements. Ian decided he hated the law and went into schoolteaching, while the well-heeled Ollie soared effortlessly into the legal firmament. Ollie has always been the dominant partner in their friendship ("I'm talking pecking order, status," Ian-the-narrator explains), and when the two couples go out for dinner, Ollie ostentatiously takes over wine-ordering duties, replacing Ian's middlebrow choices with wallet-piercing Montrachet and upmarket Chablis.

On the drunken drive back to the house, Ian and Daisy seemed to be getting intimate in the back seat... but now Daisy's friend Milo has arrived at the weekend retreat, and there's no telling where that's heading. Especially as Ollie has told Ian, but seemingly nobody else, that he has an inoperable brain tumour. But can we believe him? Whatever happens next, it'll be bad.  

• The Last Weekend continues on ITV at 9pm, Sunday 26 August