Alright. You know the drill. Girl meets boy, boy inducts girl into cult, girl falls in love with cult, cult gets a bit intense, girl flees cult, girl proceeds to have nightmarish flashbacks to her time in the cult, reality and fantasy start to break down until nobody knows what’s real or not anymore.

This is, basically, the plot of Martha Marcy May Marlene, the remarkably assured first feature from director Sean Durkin. Beginning with the eponymous Martha/Marcy May/Marlene (a wonderfully pensive Elizabeth Olsen. Yes, from that family) escaping from a farm-cum-cult compound in the Catskills mountains, the film unspools as a desperately slow burn psychological thriller. For the next hour and a half, as Martha attempts to piece together her life at a lakeside holiday home owned by her sister, Lucy (Sarah Paulson), the actual traumas of her time on the farmstead begin intruding with ever more violence into the fabric of her day to day existence. Cue nervous breakdown.

As a 100 minute portrayal of one person’s full scale mental disintegration, it probably goes without saying that Martha Marcy May Marlene is not a “fun” film. I wouldn’t, for instance, suggest you take a date to it. However, it is undeniably captivating, a masterwork of sustained tension written in slow, lingering shots, a frequent turn to silence and the irretrievably haunted Olsen, magnetic at the film’s core.

This is not a film interested in tidy answers or easy explanations, and the full scale of Martha’s experiences under the guidance of the menacing and charismatic cult leader, Patrick (a terrifically creepy John Hawkes), are left tantalisingly unexplained. Similarly so the strained relationship with her sister, whose tensions suggest a childhood irrevocably marked by the death of their parents – an event that may have set Martha on the path to eventual cult membership – but which nonetheless lingers in the descriptions allowed by a few sharp sentences. There are glimmers of detail, sly suggestions of motivation and history, but resolutely no more than we need. This is film as psychic profile, not narrative vehicle.

Full credit must go to Durkin, who won Best Director for the film at Sundance, for his willingness to drip feed information to the audience at such an unbearably slow pace. Few directors have the confidence to tell a complex story in absences, silence and fragmented suggestion, but Martha Marcy May Marlene pulses with narrative drive, a staring, insidious profile of innocence corrupted and the nightmare of self-sustaining obsession. In particular, the decision to rely on ambient countryside noise, whistling winds and the occasional menacing drone makes for a truly claustrophobic soundtrack, especially striking in a cinematic age so often marked by overly saturated sound design. The editing too, wilfully elliptical, chops back and forth between Martha’s present and past indiscriminately, adding to the sense of grim portent and paranoid delusion.

However, Martha Marcy May Marlene’s deliberate abstruseness is also its greatest impediment, occasionally strangling the picture’s momentum and coming across as evasive, rather than inspired. Piecemeal approaches can make for frustrating cinema, especially so in this film’s idling, threateningly bucolic middle stretches. Still, it would take a strong will to not be at least partly absorbed by the unsettled cadences of the story and the effort is further vindicated by one of the most properly enigmatic endings to a film in recent memory. Like, Inception wishes it was this ambiguous. And distressing.

Even so, my friend and I barely talked as we left the cinema. I think the film sort of sucked it out of us. It was emotionally arduous, sure, but also rigorously internalised, to the point where words seemed almost insufficient. I think I said “Whew” a few times and we parted quietly, lost in our thoughts. Martha Marcy May Marlene is not a perfect piece of cinema by any means, but it’s unique, compellingly composed and thought-provoking, and you could certainly do worse for a film festival outing.

- Four stars