Ronnie James Dio was a heavy metal icon and frontman of three of the best-selling, most influential and famous rock bands in history: Rainbow, Black Sabbath and his own multi-million selling band, Dio. Rainbow in the Dark is a rollercoaster ride through the extraordinary highs and lows of Dio's life, and takes us from his early days as a street gang leader and Doo-wop singer in '60s Vegas through to his breakout success with Rainbow and Black Sabbath in the '70s and the stadiums of US metal in the '80s - ending in Dio's dressing room at Madison Square Garden, in June 1986, at the peak of his worldwide fame with Dio.