Jules and Jim review – an affecting love triangle but no match for Truffaut

She has the smile. That’s the first thing to note about Sex Education’s Patricia Allison as Kath, whose enigmatic expression matches that of a goddess’s statue and leaves close friends Jules and Jim entranced. In François Truffaut’s film of Henri-Pierre Roché’s novel, that smile – deemed “innocent and cruel” by the narrator – was worn by Jeanne Moreau whose fragile femme fatale remained disconcertingly unfathomable.

Timberlake Wertenbaker’s adaptation, staged by Jermyn Street’s new artistic director Stella Powell-Jones, gives greater thought to the woman caught in the gaze of the novelist, the auteur and their title characters. As the trio alternately deepen and loosen their romances with each other, Wertenbaker keeps a compassionate curiosity about their individual behaviour but holds them to account, too. There is a heightened awareness of how easy it is to find yourself in love yet how difficult it is to nurture through the years.

Like the film, the play snips away much of the novel’s first third, which details the amorous interests of Austrian Jules (Samuel Collings) and Frenchman Jim (Alex Mugnaioni) before they fall for Kath in the years preceding the first world war. Playing it as a three-hander could feasibly have intensified the central trio but it means their other lovers – notably Gilberte and Albert – fade into passing references, softening the notion of these compartmentalised lives and defusing any sense of betrayal. Absent, too, is the bustle of Parisian cafe culture and the contrasting locations through which the story winds although Wertenbaker teases out the relationships between nations and the war’s impact on all three.

It is a well-performed show with Collings and Mugnaioni sharing a devoted camaraderie and Allison capturing the “soulquakes” of Kath’s torment. But the production needs a greater sense of danger and effervescence. Despite an interval-free, 90-minute running time it lacks the whirlwind quality of the novel and film.

The white walls of Isabella Van Braeckel’s stylish set have abstract blue lines occasionally hinting at the nose and lips of a woman’s profile and complementing Kath’s artistic career. Chris McDonnell’s lighting powerfully bathes the men in blue as they gaze at the statue whose smile she shares. If the play has a cooler overall effect than you would expect, it is an intriguing account of the ebb and flow of love, which is affectingly treated as a character in its own right.

• At Jermyn Street theatre, London, until 27 May.