Threepenny Opera is a musical play written by Bertolt Brecht with music by Kurt Weill, first performed in 1928. It is a modern adaptation of John Gay's 18th-century work, The Beggar's Opera, and critiques capitalism and social injustice through its characters and story. The plot follows the antihero Macheath, a criminal who navigates the underworld of London while dealing with love, betrayal, and survival. The work is known for its innovative use of music and theatrical techniques, emphasizing the message that society's moral decay is reflected in its economic systems.