If collecting is an art form, then a collector – like many a troubled artist — also may have his demons. Such is the conclusion of Gregory Gibson’s account of collector Bob Langmuir’s picaresque pursuit of a trove of lost photographs by Diane Arbus. Like Arbus, Langmuir was an aficionado of the “Old, Weird America” — Greil Marcus’s name for the semi-mythical demimonde of hucksters, tattooed vampires, and petty thieves who haunt the edges of American culture. As a collector, Langmuir graduated from old records to rare books to photographs and ephemera. He’s primed for the score of a lifetime when he picks up the archive of Hubert’s Dime Museum and Flea Circus, a Times Square sideshow, for a song. Entranced by the window it opens up on the world of its performers; only later does he realize that the archive include lost photographs by Diane Arbus, taken while she documented “American rites, manners, and customs” on a Guggenheim fellowship. But the very qualities that serve Langmuir so well as a collector — his intensity, fervent imagination, and talent for jive-talking — vex his relationships and confound his hopes; as Gibson’s narrative unfolds, the question of whether Langmuir will survive the struggle within himself becomes every bit as compelling as the story of Arbus’s rediscovered photographs. In the tradition of Joseph Mitchell and A. J. Liebling, this is a fine and riveting profile of troubled artists and the traces they leave behind.