Mark Siska’s documentary chronicles the birth of modern improvisational theater through the work of the short-lived but enduringly influential Compass Theater, founded in Chicago by David Shepherd and Paul Sills in 1955 as a reaction against the conservatism and complacency of the Eisenhower era. Envisioned by Shepherd as a “people’s theater”—informal, intimate, and politically engaged—Compass used the theater games codified by Sills’s mother, teacher Viola Spolin, as the basis for slyly satiric studies of social behavior. Compass only lasted a couple of years, but it launched the careers of such notables as Mike Nichols, Elaine May, Barbara Harris, and Shelley Berman, and paved the way for the sketch comedy of Second City (cofounded by Sills after Compass’s breakup) and Saturday Night Live. Lacking much in the way of archival footage (other than some sharp examples of Berman’s solo routines), the film doesn’t have a lot of laughs. Instead Siska relies on thoughtful, sometimes surprisingly confessional interviews to explore the complex and sometimes conflicted relationships that shaped Compass’s aesthetic and political identity. Besides Shepherd and Berman, the interviewees include longtime Second City producer Bernie Sahlins; theater historians Janet Coleman and Jeffrey Sweet; former congressman and judge Abner Mikva; and Compass veterans Ed Asner, Mark Gordon, Suzanne Shepherd, and Sheldon Patinkin.