Mariel Hemingway never knew her famous grandfather, Ernest, who died of a self-inflicted gunshot four months before she was born. But his ghost — and the spirits of several other Hemingways — have haunted her family for her entire life. Seven members of her extended clan, from Ernest’s father to her sister Margeaux, waged losing battles with mental illness that resulted in suicide, and Mariel herself has wrestled with her own demons. In Running From Crazy, a documentary from Oscar-winning filmmaker Barbara Kopple that premieres Sunday at the Sundance Film Festival, Hemingway tries to shed some light on her family’s tragic history and reverse a cycle of violence.

In an exclusive video clip, she takes a plunge into any icy stream. “Looking up at a mountain, listening to a river was the only time I felt sane. In the house, everything felt dead,” she says in the film. “I would often crack ice to jump into cold water. I liked anything that made me feel alive.”