In this version of the story of Joan of Arc, Brecht transforms her into "Joan Dark", a member of the "Black Straw Hats" (a Salvation Army-like group) in 20th-century Chicago. The play charts Joan's battle with Pierpont Mauler, the unctuous owner of a meat-packing plant. Like her predecessor, Joan is a doomed woman, a martyr and (initially, at least) an innocent in a world of strike-breakers, fat cats, and penniless workers. Like many of Brecht's plays it is laced with humor and songs as part of its epic dramaturgical structure and deals with the theme of emancipation from material suffering and exploitation.
(Source: Wikipedia)