Three long-form improv pieces are on the platter offered up by Theatre Momentum, and despite underseasoned moments it's mostly a tasty affair. Fugue riffs on that musical form as it interwines stories of four couples in various crises. The story takes a while to jell, but once Lisa Fairman's high-strung, resistant therapy patient is in the mix, it soars. Lost in Translation is a serviceable series of comic scenes created from a single word suggested by the audience. The ambitious, time-jumping '97 Bulldogs follows a group of small-town friends over ten years as they confront the disappointments of adult life--a smart, sensitive premise that should be impressively realized once the performers have more confidence. --Kerry Reid a Through 10/24: Wed 7 PM, Theatre Building Chicago, 1225 W. Belmont, 773-857-3858, $10-$12.