Michael Flatley, the well-oiled "Lord of the Dance," may be noticeably absent from this production, but the high-stepping troupe is ably led by Colin Dunne and Jean Butler in a live performance at Radio City Music Hall. An international cast, pounding music and quick choreography help tell the story of Irish immigrants and their journey to the New World. But a dance battle between Dunne and two African-American tappers is an emotional high point.