The book, a chronicle of Dr. Jim’s work and the city’s unsheltered population as seen through his eyes, is at its most moving when Kidder’s camera zooms in tight on the semi-dysfunctional relationship between Dr. Jim and Tony, who look to each other for solace from the horrors they’ve witnessed and experienced on the streets. As Rough Sleepers progresses, their relationship becomes its primary focus, culminating in a brutal revelation that may provide the key to unlocking the mystery of why, exactly, Tony has been on the streets so long.