Tom Burke and Emma Corrin also appear in a production at London’s Barbican that asks searching questions about art while remaining true to Chekhov

I know that’s not what you expected,” says Zachary Hart’s Simon as he dismounts from his quad bike. Neither did I expect him to whip out a guitar and start belting out Billy Bragg’s The Milkman of Human Kindness.

That’s the underlying theme to all the action, set by designer Magda Willi on a bare stage, dominated by a huge patch of rustling reeds, from which characters suddenly emerge. Atmosphere is provided by Bruno Poet’s changeable lighting, which, as the story progresses, makes the greenery cast dark shadows, enclosing the scene.

Oh, and it’s got a performance from Cate Blanchett that may well be the best of the year. ‘Who wants a bit of Chekhov?’ Zachary Hart’s dirty-overalled Medvedenko asks as he bashes out a Billy Bragg number on guitar.

Blanchett and Fassbender are very good indeed, as both seen-it-all secret agents and middle-aged spouses. Among the film’s high points are the times those two sides of their lives merge. In one, she gently chides him for putting truth serum in the lunch he’s making for the younger quartet of spies,

Michael Fassbender plays an "icy" British spy tasked with identifying a traitor in his agency. When he is presented with a list of suspects, he finds on it the name of his "beloved wife and colleague" (Cate Blanchett),

In the new espionage thriller Black Bag, Cate Blanchett and Michael Fassbender play Kathryn St. Jean and George Woodhouse, married British spies who aren’t always honest with each other out of necessity.