Thor (Baldur Einarsson) and Christian (Blær Hinriksson) are inseparable best friends growing up by the sea in rural Iceland. During the last summer of their adolescence, the boys are very conscious of their pubescent changes. Thor has a crush on local teen Beth (Diljá Valsdóttir), and tries to find ways to evade his older bratty sisters to spend time with her. Christian, meanwhile, has feelings for Thor that go beyond friendship – and these are difficult for him to reveal. As the seasons change and the pace of the local gossip quickens, both boys try to keep their flailing emotions in check.

Heartstone, a striking first feature from writer/director Gudmundur Arnar Gudmundsson, benefits from two exceptional main performances. Newcomers Einarsson and Hinriksson are searing, bringing deep emotional intensity to their roles. Sometimes, it feels almost voyeuristic to observe these youths at their most vulnerable and sexually confused. Their impulses, as they navigate a wide spectrum of feelings, rival any portrait of burgeoning young love and sexual tension in recent screen memory.

Gudmundsson uses penetrating close-ups, as well as parallel scenes in the boys’ bedrooms and around the lush Icelandic vistas, to compare their journeys of discovery. Nevertheless, there is an imbalance in the storytelling. Thor is the film’s protagonist, although Christian’s arc is more intriguing and complex. Meanwhile, although the filmmaker has the patience to let smaller moments inform the characters, Heartstone’s pacing sags in the latter half. A tightened edit with a stronger focus on Christian’s emotional turmoil would have turned an impressive début into a masterful one.