Warning: This review alludes to aspects of the plot.

As a director brought up on the movies and storytelling values of ‘40’s American Cinema, one can understand why Robert Zemeckis would be attracted to Allied; a movie suggested by and riffing off Casablanca. Indeed, that’s where it starts, with WW2 Canadian Wing Commander Brad Pitt parachuting into enemy territory to hook up with resistance contact, Marion Cotillard. Their mission is to play husband and wife while preparing to assassinate the German ambassador but in the course of living in close quarters and with the threat of death imminent, role play becomes real romance.

Later, ensconced in London with a baby born during a Blitz raid on the hospital (it’s like the Germans are trying to tell Pitt something), the now married couple’s future happiness is thrown into doubt when she’s identified as a possible German spy. Pitt, who’d ignored the early signalling of Cotillard’s duplicity, her notes on espionage like using real emotion to copper plate the illusion, her forensic attention to detail – especially accents and expected behaviours, and her loose talk of having no plans beyond the war (suggesting a lack of optimism about her long term future), is duty bound to establish her guilt then execute her to avoid a charge of collaboration. An old fashioned thriller based on a wartime relationship then, and one that in Zemeckis’ hands is content to unfold at a retro pace.

The long first act, in which the pair bond and assort with Nazis and French locals under the Moroccan sun is evocative enough of Casablanca, or at least our cultural memory of it, to prompt speculation on which of its many iconic elements will be reworked in the movie to come (it would be inconceivable that a modern movie could refer to nothing but itself). Ultimately there’s a new twist on “play it again”, with a piano tune becoming a major plot point, and a climax on an air field in which a doomed couple once again try to flee from the imminent threat of capture.

All of which is fine and, as we’ve come to expect from Zemeckis, well crafted, but Allied has a ruinous deficiency that robs the movie of the psychological intrigue and emotional fallout that one imagines both writer Stephen Knight and the Back to the Future director had in mind. Brad Pitt, perhaps aiming for stoic and controlled, is stiff in a lead role that demanded somebody’s A-Game. Whereas Cotillard manages to be mysterious and unreadable, particularly in the first act where her character’s on an equal footing with her male co-star’s, Pitt is distant and mannered throughout, as though his mind were on his dissolving real-world marriage.

Was the leading man too blitzed on bentines, as tabloid innuendo suggested, to turn in a performance? We may never know, but the effect is a charismatic and psychological void where his character should be. Pitt in detached mode can’t sell the movie’s big moments – his doubts, fears and the disaster that threatens to destroy his family. He’s a passion free zone.

It’s a problem because we need to believe in these step changes to stay invested in the story, not least because of Zemeckis’s unwise decision to scale back Cotillard’s vivid presence in the second and third act. With the female lead reduced to cooking, fucking and child rearing, while being careful to retain an air of elusiveness, the baton’s in Pitt’s clammy hands, but it’s dropped and consequently those elements that might have remained in the background, if the performances were big enough – plot mechanics, minor characters – are that much more conspicuous. That’s bad news for a movie paced like an oldie.

Despite these difficulties, Allied is a solid WW2 thriller that thanks to Zemeckis’s careful orchestration, boasts an assortment of memorable moments and the director’s usual seamless blend of live action and digital effects. One can only imagine his frustration at getting a lead like Brad Pitt, only to see him tank on camera and sap the story’s energy. If only he’d had the time and inclination to retool the script to bring Cotillard to the fore in the London sections, but as the film teaches us, it’s one thing to wish for something, another to get it.