What did it mean to photographer Michael Ackerman and filmmaker Jem Cohen to ring the bell beside the singular green door of Robert Frank and June Leaf's timeworn home on New York's Bleecker Street? Or for Cohen to traverse dirt roads to their equally weathered house high above the ocean in Nova Scotia? First as newly developing artists and then across decades, it meant taking a chance-would it be an intensely beautiful encounter or a sad dismissal, a life-changing inspiration or a sorely missed moment? Visitors reflects on Cohen and Ackerman's times with Frank and Leaf, the artists who mean most to them in the world, via a scrapbook of their photos and filmstrips, alongside letters, postcards, and drawings by Robert and June. The book is an intimate and revelatory interchange marked by both lightness and weight. Cohen describes "warrens of tumbling rooms and staircases, museums of memories, crossed paths, dust, and souvenirs," the homes of the "living contradictions" Leaf and Frank: June, engrossed in her studio work and less encumbered than her husband by "all the renown and history going around, some of it heartbreaking"; and Robert, "the world's most famous and famously difficult photographer, as well as reclusive, even if that wasn't exactly true." Ackerman and Cohen's images of the two are candid, empathetic, and aesthetically daring: June and Robert thinking, laughing, waiting, working, watching the world go by. Including a Blu-ray film of a yet unreleased documentary film about the couple by Cohen, Visitors is a tribute to two friends and a gift for all of us who never had the chance (or nerve) to ring the bell by that green door.