Helix, One Group Mind, at ImprovOlympic. The Harold–the preferred long-form training method among Chicago improvisers–is the house specialty at ImprovOlympic because it sets all performers on a relatively level playing field. Experienced improvisers stand to learn just as much as newbies by bowing respectfully to the group aesthetic, and the egregious showboating that colors some of the theater’s less structured efforts rarely crops up in its Harold-based shows. Quality control is assured by the knowledge–shared by the audience and team members alike–that staying true to the spirit of exploration frequently yields intriguing results.

Teams DeWitt and the Teenage Carthrobs make the most of the format with Helix, which features the two groups individually riffing off the same suggestion in sequential Harolds before joining forces for a free-form third act. On the evening I attended, DeWitt applied rich character-based scene work to the audience suggestion of “platypus,” from which the Carthrobs drew out an underlying theme of “nature vs. nurture,” displaying sharp physical instincts. The third act–which followed a brief intermission–proved both troupes adept at finding natural points of convergence between the characters and tone of the two pieces. The charming, subtle results owed as much to James Watson and Francis Crick as Del Close and Charna Halpern.