A grandmother. A source of existence. A portal to other worlds. For thousands of years, the Indigenous Peoples of what is now known as North and South Dakota co-existed reciprocally with the Missouri River, its waters offering life while also inspiring legends and languages. In Tahnaanooku’, filmmaker Justin Deegan takes an experimental approach to the severing of this relationship between his community — the Mandan, Hidatsa, and Arikara — and the river, the result of over 80 years of US government efforts to control the Missouri, including via the Garrison Dam.

Seen through the eyes of Deegan’s mother, Darline, Tahnaanooku’ intertwines past, present, and future, land and language, dreams and reality. The staunching of the Missouri contrasts with a fluid streak of horses, the diminished river currents interweave with the light of the aurora borealis. In dreams, Darline — a designer, activist, mother, and grandmother — receives messages from the original Mother, Earth itself. Meanwhile, the stark visual backdrop of the Garrison Dam offers an immovable reminder of the ruinous history of the Pick-Sloan Plan, deemed by legendary historian Vine Deloria Jr. (Standing Rock Sioux) to be ”the single most destructive act ever perpetrated on any tribe by the United States.” Glimpsed in ceremony, Darline (one of the last speakers of the critically endangered ancient Arikara language) offers care to a fellow grandmother and shares hope for the generations to come.