There are several huge shows at PS1 right now — Francis Alys, Ryan Trecartin, Interboro Partners — but it's Grossman's focused, intense and arresting series of S&M-inspired leather masks from the 60s-80s that offer perhaps the most satisfying experience. The 14 sculptures on view evoke at once a Native American mask ritual and a hardcore leather bar: zippers, straps and chains crisscross certain pieces, while others sport horns and similarly surreal appendages.