Opening with a solemn quote from the Qur’an defining “Barzakh” – a liminal space between the dead and the afterlife – Alejandro G Salgado’s sombre documentary evokes the same atmosphere of indeterminacy, creating both a geographical and emotional state of perpetual longing. Shot entirely at night on the coastline of Melilla, which turns otherworldly once darkness falls, the film observes, often from a distance, young and undocumented Moroccan boys who are waiting and hoping to cross to Europe.

Hiding among the cavernous hollows of the rocky cliffs of this tiny Spanish enclave, these boys are wrapped in shadows. Besides hiding their identities, the nocturnal cinematography also points up the stark outlines of their makeshift shelters, which seem to swallow their small figures whole. The boys sing traditional devotional songs together: the gentle yearning sharply contrasts with the cacophony of the ocean waves, suggesting the arduous journeys on which they will soon embark.

Their talk is of everyday survival, such as catching fish for food or how to keep themselves warm with a fire stoked only with cardboard. Weary of the cold and unforgiving nights, they are also fearful of the dangers of sneaking on to boats to get to Europe. Barely adults themselves, the boys even dream about raising kids. It is this mirage that nudges them onwards through a seemingly unending limbo.

While the broody cinematography is at times a tad impenetrable, and the film comes close to overly poeticising its subjects’ experiences, this documentary remains a poignant watch, highlighting the psychological and physical toll of border crossing.

• Barzakh is released on 15 October on True Story.