Nine years after The Last Things, Irene Dionisio returns to fiction with Idda, which has world-premiered in the Platform competition at the Toronto International Film Festival. Its title means “she” in Sicilian and is also a familiar way of referring to Mount Etna, whose presence hangs over the film not merely as scenery, but also as an unstable, almost sentient force.

Adele (Tecla Insolia) and Sofia (Romana Maggiora Vergano) were inseparable as children, but adulthood has pushed them onto different paths. Reunited after a long period apart, they set out to fulfil an old promise and climb Etna together. The trip initially has the loose, spontaneous air of two friends trying to rekindle an intimacy they assume is still there. Yet small irritations, silences and unresolved memories gradually make it clear that what binds them may now have more to do with their shared past than with who they have become.

This is where Idda is at its most convincing. Dionisio, who co-wrote the screenplay with Marco Borromei, avoids turning female friendship into either uncomplicated sisterhood or outright rivalry. Instead, she captures the less dramatic but more recognisable discomfort of discovering that someone who once understood you instinctively has become partially unknowable. The film is also firmly rooted in a contemporary inability to communicate: Adele and Sofia speak, argue and reconnect physically, but repeatedly fail to articulate what they actually need from one another.

Insolia and Maggiora Vergano carry that uncertainty extremely well. Both performances are marked by fragility, but in contrasting registers: Adele is more inward and watchful, while Sofia appears freer and more impulsive, even when that ease begins to look like another defence mechanism. Their chemistry makes the friendship credible even at moments when the viewer may reasonably wonder why these two people are still friends at all. The answer seems to lie precisely in memory, habit and the emotional geography of having grown up together.

Gergely Pohárnok’s cinematography is equally attentive to avoiding obvious shorthand. Sicily, refreshingly, rarely looks like the Sicily of postcards or tourist-office campaigns. Much of the urban landscape could belong almost anywhere, while the island asserts itself most forcefully through nature and, inevitably, Etna. The volcano’s ash, rock, smoke and vastness steadily displace the everyday world, allowing the film to move from an intimate friendship drama towards something more uncanny. A particularly striking final sequence pushes this transformation the furthest, reaching an otherworldly register without abandoning the emotional perspective that has guided the film.

Yet Idda does not dig as deeply as its strongest passages suggest it might. The screenplay withholds a great deal, sometimes productively, but at other points one wishes to know considerably more about Adele and Sofia, their years apart and the reasons behind certain choices made both on and off screen. Some revelations therefore carry less weight than intended, while the central Etna metaphor occasionally risks becoming overly explicit.

Still, Dionisio’s latest effort remains a sensitive and formally accomplished portrait of a relationship whose importance cannot be measured simply by whether it still “works”. Its most persuasive idea is also its simplest: people change, friendships mutate, and sometimes what survives is neither complete understanding nor even compatibility, but the residue of having once known another person completely.

Idda was produced by Kino Produzioni together with Rai Cinema, Andromeda Film, EDI Effetti Digitali Italiani and Wise Pictures. Rai Cinema International Distribution handles its world sales.