The latest Milwaukee Rep production tells the story of a once forgotten blues record label in unassuming Grafton, Wis. Grafton City Blues, which debuts in the Stackner Cabaret tonight with an 8 p.m. performance, documents the depression-era label Paramount, which released sessions from future legends like Blind Lemon Jefferson, Ma Rainey and even Louis Armstrong. The play is set in a modern-day Bronzeville attic, where relics from the label are discovered.