In 2007, a would-be artist turned estate agent named John Maloof bought a box of photographic negatives at a Chicago auction for about $400. He was writing a book about his neighbourhood and looking for photos to accompany his text. When Maloof began scanning the negatives two years later, he was surprised at the quality of the pictures. A Google search revealed nothing about the photographer, Vivian Maier, except that she had recently died, so he posted some of her photos online. They went viral. In the intervening years, Maier has been acclaimed one of the greatest street photographers of the 20th century – and revealed to be a nanny who took many of her photos while escorting her young charges. An aura of mystery often swirls about her, as evinced by the 2013 documentary Finding Vivian Maier by Maloof (and Charlie Siskel), who now curates her work.

In this dogged new biography, Ann Marks purports to clear things up: ‘“Who was Vivian Maier, and why didn’t she share her photographs?” Mystery solved.’ Can a life be summed up so tidily, though? Marks’s questions are basically unanswerable and her attempts to find solutions to them can