An enigma, something mysterious or puzzling, asks us for explanations. In this exhibition, the black-and-white photographs by Ruth Bernhard, Jennifer Schlesinger, Paul Caponigro & Neil Folberg—playing in the obscure space between understanding and incomprehension—do just that. There’s a silhouette of a child underwater, a lone window refracting light, a haunted house. What do they mean? —E.C.