“I’m going to kill him,” Judy Garland once said of the director John Cassavetes, who liked to keep his actors “off balance” because he believed that “from nervousness would spring spontaneity.” His philosophy upset Garland, but it inspired audiences—and this show coming to BAM. Based on a Cassavetes film, in which an actress’s spiral into madness produces volatile yet vitally authentic performances, the Second Woman, an experiment in “endurance theater,” puts Cassavetes theory to the test. One actress plays the same scene for 24 hours, each time with a different partner, and each time with unpredictable results. —C.J.F.