Over the last fifteen years, there have been two quite distinct tendencies in Robert Zemeckis’ body of work. On the one hand, as befits a director who made his name as a special effects innovator, there has been a steady experimentation with 3D cinema. Years before James Cameron released Avatar and Martin Scorsese released Hugo, Zemeckis had directed The Polar Express and Beowulf, following them with A Christmas Carol in 2009 and The Walk in 2013. At the same time, there has been another trend in Zemeckis’ body of work that came into its own with Cast Away and What Lies Beneath, both released in 2000. Here, Zemeckis experimented with heightened states of isolation as a kind of special effect, building an intensified naturalism that was just a little too airbrushed, polished and digital to ever feel exactly realistic, or exactly naturalistic. In these films, traditional special effects are somewhat beside the point, since they take place in a hyper-real space in which the difference between reality and augmented reality has largely dissolved, forcing their protagonists to continually reassess their perceptions at every juncture.

Of course, there is a fluid relationship between these two tendencies, with the digital isolation of Zemeckis’ more “naturalistic” films speaking quite eloquently to the atomised audience produced by 3D glasses and 3D spectatorship. In the case of The Walk, both tendencies were completely fused, making for the first 3D film to really seize upon isolation as its subject matter, along with one of Zemeckis’ most fully-rounded films of the new millennium. As if acknowledging that as a high watermark, Zemeckis moved away from 3D with Flight, and has largely moved away from spectacle with Allied, which plays as a kind of spiritual successor to What Lies Beneath. In other words, it feels as bit like Zemeckis’ digital experimentations have come full circle, taking us through the most extravagant and flamboyant 3D excursions to the unearthly hush and unworldly stillness that presided over his first film of the digital era. Personally, I’ve always found What Lies Beneath far more uncanny and compelling than any of his 3D features, just because of how seamlessly it blends analog and digital styles, until everything across his mise-en-scene feels completely naturalistic and completely synthetic at the same time. Defying you to be seduced by its surfaces, but leaving nothing but surface, it’s a film that feels even more unsettling in retrospect, accentuating everything that is naturalised and invisible in our current digital era.

If Allied is a period piece, then, it feels as much a reflection upon this early period of Zemeckis’ own filmography as the World War II backdrop against which it takes place. Thanks in part to the focus on espionage, this historical context all but vanishes into a series of cinematic quotations over the course of the narrative, with the first act, in particular, playing as a sustained riff on Casablanca, in which we’re introduced to Max Vatan (Brad Pitt), a Canadian officer, and Marianne Beausejour (Marion Cotillard), a member of the French Resistance, who are charged with playing the part of a couple in order to infiltrate the German Embassy in French Morocco and assassinate the Ambassador. Throughout this first act, Zemeckis pointedly uses CGI, especially in and around sandstorms, to remove everything to a grainy, granular distance from Max and Marianne’s relationship, which evolves, somewhat predictably, into a full-blown romance. With all the historical texture cloaked in a misty, distant kind of feel, this part of the film often reminded me of Boardwalk Empire in the way in which it seems to draw on the background ambience and synthetic murmur that often generates atmosphere in historical role-playing games. As a result, it’s most evocative when Zemeckis’ shrouds the couple in spaces that are already semi-abstracted to begin with, especially the roof of their Casablanca apartment, where they get to know each other against a backdrop of free-floating lights and half-glimpsed fragments of cityscape.

Of course, this is an espionage thriller as well as a study in digital atmosphere, and the assassination proceeds with all the narrative ingenuity you might expect. Yet there is something about this digital dissolution of space and time that also seems to slow down suspense as well, so it’s not entirely surprising when this first act is abruptly cut short and the action switches back to England, where Max and Marianne get married just as abruptly and settle down into a bucolic life on the outskirts of London. After an opening act that confined itself to a few tense days, the film suddenly traverses what appears to be an entire year in the course of a few minutes, creating a quite uneasy and vertiginous tone that does away with any semblance of historical realism or historical spectacle. I have to confess that, at this point in the film, I was pretty disappointed, since it also appears as if Zemeckis is going to move in the direction of straightforward historical romance, or at least only continue the espionage angle through the fairly heavy-handed romanticism within which Max and Marianne are framed over the course of this abbreviated second act.

What ensues, however, is a brilliant turn in which British Intelligence abruptly inform Max that Marianne may have been a German spy all along, despite the fact that she fought alongside him and is now married to him and the mother of his son. At this point, Allied settles into what it really is – a domestic espionage thriller – by way of an extended third act that takes place over the seventy-two hour period that British Intelligence require to perform a “blue dye test” on Marianne to check whether she is in fact feeding information to the enemy. With most of the subsequent action set on the home front – and, literally, in and around Max and Marianne’s home – a procedural quality comes into play that feels modelled on Michelle Pfeiffer’s peripatetic investigation into Harrison Ford in What Lies Beneath, as Max searches further and further afield to try and figure out what is happening right under his own nose. In one of the most memorable developments, his determination to have a photograph of Marianne verified leads him through a whole host of possible informants, culminating with him taking a night plane to Dieppe to check her identity with one of the last remaining members of her Resistance outfit. Even that proves inconclusive, however, as Max becomes more and more isolated – isolated from Marianne, from British Intelligence, from his own past – to the point where only Zemeckis’ heightened digital naturalism feels commensurate to his dislocation from the spatial and temporal demarcations in his life that he has previously taken for granted.

Among other things, that seems to mark a bit of a shift for Pitt as an actor, and not just because his reputed relationship with Cotillard also turns this into something of a sombre, late career sequel to Mr. and Mrs. Smith. One of the key hallmarks of Zemeckis’ interest in isolation is his interest with utterly inscrutable, unreadable faces – faces so opaque that they may as well be digitally generated. In the case of Allied, that’s obviously most pronounced in the way in which Cotillard holds herself, making for one of the very best (if one of the most understated) performances of her career. In the case of Pitt, however, it draws the materiality and surface striation of his skin into relief in quite a stark and naked way, which is perhaps why this is the first film I’ve seen in which Pitt has really looked old. Granted, his more recent films have been anxious to imbue him with the gravitas that comes with old age – especially his war films – as if to pre-empt and contain the confronting possibility of an aged version of Brad Pitt. But here Zemeckis presents the age without the gravitas, which isn’t to say that Pitt’s character is comic or bathetic, but that there is a profound uncertainty and caution that, once again, recalls Pfeiffer in What Lies Beneath, and makes the weathered textures of his face and skin more apparent than they might have otherwise been.

For a film that is so preoccupied with lateness, finding an adequate conclusion was always going to be a challenge, so it’s impressive that Zemeckis strikes a tone that manages to create some closure without betraying the sombreness and heightened isolation of the film as a whole. In a climactic and convoluted series of scenes, it emerges that Marianne was originally German, then turned for Max, then once again turned for a community of German expatriates in London who were blackmailing her. After Marianne shoots herself to exonerate Max – and to prevent him having to execute her himself, as was the custom at the time – it all seems to be quite neatly wrapped up. But, given that Max’s isolation simply deepens over the final images, questions start to emerge. Did Marion “turn” before or after falling in love with Max, or before or after their marriage? Did she already have doubts by the time she had arrived in Casablanca? By leaving this aspect of the timeline deliberately vague, Zemeckis ensures that the romance is never fully extricated from espionage, even in retrospect. For all that the ending promises to spatially and temporally demarcate the events of the narrative, and to extract some genuine naturalism from their intensified naturalism, it just immerses and isolates us further in them, making for one of the most melancholy films in Zemeckis’ career, as well as one of the most melancholy films I have seen about World War II.