During the Great War, collectors Walter and Louise Arensberg hosted a variety of European artists at their Manhattan apartment, and the mysterious Marcel Duchamp was foremost among them. Creating the painting Nude Descending a Staircase and the "readymade" art piece Fountain—actually a urinal—Duchamp gained notoriety, but also lifelong admirers. Here Ruth Brandon charts the Frenchman's complex ménage ? trois with ceramicist Beatrice Wood and future Jules and Jim novelist Henri-Pierre Roché, a relationship with profound implications for these free spirits and for modern art itself.