Vivian Maier’s photography has had a seismic effect on the art world since it was discovered a few years ago. The poignant story behind the work enhances its appeal: Maier was one of the finest street photographers of the mid-twentieth century, yet she kept her work hidden and died in poverty. In fact, she worked as a nanny for her entire career, living with a succession of suburban families and becoming increasingly eccentric. Her employers knew her as a shutterbug, but it was only after her death that the amazing quality and breadth of her work was discovered.

Maier’s photography, and her fascinating story, would never have come to light if not for John Maloof, a young Chicagoan who happened across a trunk of her negatives at a local auction house. In the absorbing new documentary Finding Vivian Maier, Maloof traces the story of his find, and the obsessive quest he went on to solve the mystery behind the treasure trove of images Maier left behind.

The film, which is both unsettling and delightful, offers a compelling, bittersweet portrait of a very complicated woman. A veritable Mary Poppins figure to some of the children she worked with, Maier was abusive to others. She was extremely wary of men, in a way that suggested she might have been abused herself. Often she refused to give her name and occupation to people, referring to herself as “the mystery woman” or “a kind of spy.”