Blending science fiction and magical realism, environmental catastrophe and family secrets, Francisca Alegría’s heady mystery is an ambitious and murkily atmospheric debut. Set in Chile, this Spanish-language picture takes a real-life event – the pollution of a river by a paper mill – as a jumping-off point. The disaster kills fish and wildlife, but it reanimates Magdalena (Mía Maestro), who drowned in the river many years before. Mute, Magdalena now communicates through digital technology. The tech-fantasy crossover has a kinship with the recent Neptune Frost, but most of all this film about motherhood and natural balance has unexpected parallels with Andrea Arnold’s Cow.