The long-running comedic and interactive Shear Madness, which celebrated its 35th year of performances in Boston, is adapted by Bruce Jordan — who also directs the Off-Broadway staging — and Marilyn Abrams, from Paul Pörtner's German psychodrama. The show is set in a unisex hair salon where a murder takes place. The audience is invited to vote nightly on who is guilty and who isn't, producing varied results.