One of these years, Javier Marías will probably win the Nobel Prize in Literature. If and when that honour happens, critics may well discuss the Spanish writer’s fiction, in all its “intensity, complexity and power to convince”, in much the same terms as he applies to one of his favourite works of art.

Icelandic writer-director Gudmundur Arnar Gudmundsson has made an impressive feature debut with this story of crossing the threshold from childhood to young adult experience. Heartstone acutely and empathetically catches the path from innocence to experience of its two 14-year-old protagonists, Thor (Baldur Einarsson) and Kristján (Blær Hinriksson), in which the film’s twin themes, coming of age and coming out, become uneasily intertwined.

Gudmundsson opens his story at a leisurely pace – and, at a few minutes over the two-hour mark, there’s no calling its rhythm hurried – as we discover the world in which the two teenagers live. It’s the summer holidays, and they’re loping around with friends, fishing from the harbour side of the remote village that is home. When a shoal of fish swims by unexpectedly, the kids are soon struggling to pull them out of the water fast enough, before casually bashing them to death on the concrete. It’s an indicator that nature here is coloured by tooth and claw (an allusion referenced literally in one early visual), without overmuch room for sentiment. Such a mood will colour the human development that follows, too.But this is also nature, in the sheer physical sense, at its most impressive (pictured above). The craggy coast around the cluster of houses that makes up the isolated village rises up towards spectacular mountains, which somehow dwarf any human activity with their scale. In summer, as the light stretches around the clock, the beauty is awesome, memorably captured in Norwegian cinematographer Sturla Brandth Grøvlen’s widescreen vistas. But we sense that when winter comes – Heartstone closes as the first dusting of snow falls – the cold isolation of the place will be as complete as the luminous airiness with which it seasonally alternates.

Coming-of-age stories like this, especially from Nordic and Scandinavian climes, are almost a trope of cinema, often defined by the gentleness of their revelations, the sometimes quirky benignity of their settings. Gudmundsson consciously avoids any such tenderness, with nature’s cruelties mirrored in the immediate human environment, like how the village’s older teenagers tease the younger generation. There’s a similarly sharp atmosphere at home, with existence for the sensitive Kristján dominated by a hard-drinking father, and family life for Thor – the nice irony of his name is emphasised by the fact that, though he’s determined and tough, he’s still a minnow in size – coloured by two elder sisters who are as unforgiving with him as they are with their single mother (Nína Dögg Filippusdóttir, a lovely performance).

The father has gone off with a younger woman, and any sympathy for their mum's tentative attempts to find someone to date in this backwater is notably lacking. We see what it involves for her when the adults get together for the village-hall dance – a thrash, if ever there was one – and her attention falls on the outsider Sven (Søren Malling, a visitor in every sense: he’s Torben, from Borgen). Nevertheless there’s a sense of tough-love affection in this family unit that is finally reassuring, as well as an element of comedy to the sisters, Hafdis (Ran Ragnarsdottir) particularly; she writes poetry of Plath-like intensity that she reads out at meals.

Contrasting yet complementary female company comes with Beta (Dilja Valsdotttir) and Hanna (Katla Njalsdottir, pictured together above), with whom the boys tentatively explore the first hints of sexual consciousness at furtive sleepovers, which come with games of Truth or Dare, the forfeits precipitating different kinds of intimacy. Gradually the unsuspecting best-friend closeness between Thor and Kristján becomes something more complicated, though the scenes of revelation are laced with a lightness that allows for it all to be treated as game-playing. The ramifications become clearer in an episode in which the four of them go camping on their own in the mountains, where the landscape itself seems to pull a response from Kristján that he somehow can’t resist.

Gudmundsson treats the repercussions of his story with understated sensitivity: Heartstone may have won the “Queer Lion” at last year’s Venice film festival, but the sexuality here is one of exploration rather than action (Céline Sciamma’s Tomboy is one other such film that comes to mind). In all such tales of the growing self-awareness of youth, the quality of the playing from the young cast is crucial, and Gudmundsson has drawn hugely sensitive performances from his two leads. The landscapes that surround them may be monumental and memorable, but the sincerity and naturalness of these two performances is almost microscopically exact.  

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Overleaf: watch the trailer for Heartstone

The Viennale is one of the best film festivals in the world and an indispensable part of Vienna’s cultural life. Yet this year’s edition was launched amid trying times.

While bird-lovers will certainly not be disappointed by Portuguese auteur João Pedro Rodrigues’ new film, the ambitions of The Ornithologist stretch considerably beyond such avine fascinations. Its opening title, “Whoever approaches the Spirit will feel its warmth, hence his heart will be lifted up to new heights,” ascribed to St Anthony of Padua, hints at a distinctly sacred element, and in fact Rodrigues’ film is (very) loosely based on the life of that saint, the patron both of the director’s native Lisbon and of the lost, another theme that becomes central to his film.

That is not, however, our first impression of the film’s protagonist Fernando (played by French actor Paul Hamy) as he methodically prepares for a day’s bird-watching in an isolated nature reserve, its remoteness defined by the unreliability of any mobile signal; Fernando ignores messages that come through from his presumed partner, who is concerned about his welfare and, in particular, whether he’s taking his medication. Instead he’s determined to enjoy his solitude in this stunningly beautiful landscape, canoeing down the river through high gorges, observing the impressive variety of birds that wheel overhead; his interests clearly go beyond those of the amateur, and he records his observations into a tape-recorder (ornithology was a passionate interest of the director in his youth).But this absorption means that he fails to notice approaching rapids in the river, and the next thing we know his body is found by two Chinese girls who are hiking through the thick forest, obviously very lost indeed from their Santiago pilgrimage route. From here on the tone of Rodrigues’ film moves ineffably towards the bizarre and spiritually highly-strung: when Fernando wakes up next, he’s been trussed up with ropes, à la St Sebastian, by the pilgrims. Narrowly escaping that one, his attempts to find his way back to civilisation (whatever that might mean in such a context) seem doomed, every new encounter stranger than the last.

Climbing cliffs and negotiating the rocky river bank, he finds that the wreckage of his canoe has become a kind of shrine (main picture), and witnesses strange night-time rituals that hint at a pagan world. (Knowing that these are being conducted in Mirandese, Portugal’s rare minority language, and that the multi-coloured rag vestments are part of the careto ritual may not sufficiently alleviate the viewer’s sense of bafflement.) An unexpectedly sexual tryst ensues with a deaf-mute goatherd (Xelo Cagiao, pictured above with Hamy), turning suddenly violent in a manner that would certainly have intrigued Derek Jarman.

Though Rodrigues himself may not be a believer in any usual sense, there is certainly a sacred quality to the conclusion of his film, which sees the director himself step into the role of his protagonist

But it’s when, around the 100-minute mark, Fernando is pursued by bare-breasted horseback Amazon warriors speaking Latin that The Ornithologist finally loses any semblance of connection to the world as we traditionally know it. The observation delivered at one point here, "There are certain things we shoudn't try to understand", has rarely rung truer. Though Rodrigues himself may not be a believer in any usual sense, there is certainly a sacred quality to the conclusion of his film, which sees the director himself step into the role of his protagonist, as Fernando becomes known as Antonio: the change of name mirrors that of the life of St Anthony, and for those still keeping up there are other episodes from the life of the saint that are referenced, including his talking to the fish.

It’s certainly weird, and rather wonderful. A sublime coda takes the protagonists, Chinese pilgrims included, somewhere else altogether, that closure set to the magnificently secular anthem of Antonio Variacoes’ Canção de Engate; until that point the spare scoring has involved anxiously strangled string sounds from French cellist Séverine Ballon (development on The Ornithologist was slowed by Portugal’s financial crisis, and it became a coproduction with France). Cinematographer Rui Poças, known for his work with Miguel Gomes on Tabu and the wonderful Our Beloved Month of August, catches both the glories of the film's landscapes and the increasingly hallucinatory strangeness of its later action. (After all, we may wonder whether what we have been witnessing are psychotropic figments of Fernando’s imagination, brought on by his not taking his medication).

Rodrigues himself has described what he was aiming for in the film as a “Pasolini-type” Western, and in the sense that we follow an unusual journey that ends in a degree of enlightenment, it’s an allusion that is more helpful than confusing. The Ornithologist won Rodrigues the Best Director award at last year’s Locarno festival, and the film is quintessential festival fare: it certainly won’t win over all viewers – indeed, as a multiplex-emptier it would be unsurpassed – but for those who are persuaded, its eclectic fancy should exert an oblique fascination.

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Overleaf: watch the trailer for The Ornithologist