The Souvenir is not the film you think it is. Joanna Hogg’s semi-autobiographical tale of a young woman who falls under the sway of an older man, with consequences both tragic and essential to her artistic development, is ostensibly one we’ve heard many times before. In recent years, Lone Scherfig’s An Education would seem its closest touchpoint – and indeed, may have the same effect on the career of Honor Swinton Byrne as the latter film did for Carey Mulligan.

This, however, is a misleading comparison, not least because Hogg’s film is a far stranger thing. Shot in the same unapologetically minimalist, near cinema verité style as her previous works Unrelated and Archipelago, The Souvenir consistently revels in the disjunction between what it is and what it purports to be.

The film is set up so that we think of it as a literal souvenir, the memory of an actual relationship. At first Hogg’s aching attention to detail, coupled with immaculate period detail, encourages carries us along in this belief: the story of Julie (Honor Swinton Byrne) and Anthony’s (Tom Burke) courtship, told through a series of vignettes – lunches at Harrod’s, weekends with parents in various country piles – is so vividly realised, so easily recognisable, that we are conned into believing what we see.

But as the film continues – at almost exactly two hours, it is a true slow-burner – we gradually become aware of the contradiction between artifice and memory that sits at its core. As Julie and Anthony talk and eat, sleep and fight, they become less, not more, recognisable to us, and what first appears as a film of intense social realism becomes, in the combination of its utter clarity of artistic vision and its tonal muteness, something closer to an act of scientific observation, or perhaps a still life, than one of memory.

Julie and Anthony appear to us as if through an observation jar: though we can see through the glass, they are somehow separate from us. In their own ways, Swinton Byrne and Burke both excel in depicting this sense of refraction. The former plays Julie as a young film student desperate to throw off the constraints of her privileged upbringing, but unsure quite how to do so: at first, an earnest documentary-style feature about working-class Sunderland is her means of escaping, soon to be replaced by the mysterious Anthony.

In the latter role, Burke is impossibly charismatic: he attaches to Anthony a shabby, doomy glamour that marks him out not only from every other character, but even time itself. The Venice sequence makes this clear, a Gothic fever dream of tapestries, palazzos, and illicit passions which has more in common with the paintings of Henry David Fuseli than the rest of the film, with Anthony somewhere between impoverished English aristocrat and vampire.

When it comes to the depiction of Anthony’s addiction, Hogg prefers suggestion, at least for the first half of the film. In focusing on the smaller details – a conversation turned into an argument for no apparent reason, a seemingly innocuous request to borrow money – she shows how Anthony’s drug abuse doubles with his emotional abuse of Julie. By the time she has realised what’s really going on, she is dependent on him, and he on her.

It’s to the immense credit of both actors that they do not lean on this addiction as a crutch, as another film might: Anthony and Julie remain as sharply drawn, even in the increasingly intense final scenes. Here, Hogg’s unflinching treatment of this abuse is crucial: she presents it dispassionately, as fact, leaving us to draw our own conclusions and resisting the emotional keynotes beloved of the addiction drama.

We are left to decide for ourselves how Julie’s love affair informs her artistic development, or vice versa. By the film’s closing stages, we get the sense that she is somehow changed, not least in her cinematic aspirations: Sunderland has been left far behind, replaced by increasingly picaresque projects with her classmates. Julie is also, by now, far more clearly a foil for Hogg: in one striking scene, she stares directly into the camera, the observed transformed into the observer before our eyes. It’s a dramatic moment, and one that completely shifts the balance of power in the film.

At one point, early in their courtship, Julie tells Anthony that she wants to make a film that is “fiction, but about real people”. It’s a throwaway thought, the half-developed idea of the kind that students have, but also perhaps the best description of Hogg’s film. We can recognise the characters and the relationship, and even the world they live in, but we know it’s not true. It is a portrait, and as with all portraits, it reveals what the artist wants it to reveal. And once it does, it’s very difficult to get it out of your head.