“Fancy Dance,” the debut feature film from Erica Tremblay, begins where most films of its ilk might find their story’s second act. Tawi, a mother of a teenage daughter, has been missing for weeks. Search parties have been combing the fields, and her sister, Jax (Lily Gladstone), has struggled to get the F.B.I. to assist.

The ghost of Tawi, in other words, is a fixture from the start and hovers over the film. The empty space of her — we glimpse her only in photos and fliers — is intentional: This story about the search for a missing woman on the Seneca-Cayuga reservation of Oklahoma is not a mystery thriller, and the film is not meant to milk dramatic tension from her disappearance. Rather, Tawi’s case is all too common, and the entry point to what is ultimately a portrait of desperation, poverty and hard-won hope.

Hope, or the illusion of it, is worth fighting for because of Roki (Isabel Deroy-Olson), Tawi’s daughter, whom Jax has been taking care of since Tawi went missing. The two are close, forcing Jax between two poles: the hardened exterior that reservation life necessitates (Gladstone is imperfect, but well suited to Jax’s steel-encased tenderness) and the desire to preserve Roki’s innocence. Even as they commit petty crimes to scrounge up cash and continue the search, Jax assures Roki that her mother will be at the upcoming annual powwow, where there is a mother-daughter dance.

Tremblay’s film is not always graceful — the dialogue and acting can be stilted, and one hopes for a little more formal rigor — but it’s a strong debut undergirded by a palpably real emotional core and an un-showy sense of the reality of reservation life. Jax is often confronted by a push and pull in the same room: those ready to pounce and those offering to help. Each stance is born out of the same understanding — that the world is harsh, and not everyone can survive it.

Fancy Dance
Rated R for language, some drug content and sexual material. Running time: 1 hour 30 minutes. In theaters.