Mamma Mia! is a film adaptation of the West End stage musical, based on the songs of successful pop group ABBA, with additional music also composed by ABBA member Benny Andersson. Despite opening in the USA on the same date as the critically acclaimed Batman sequel 'The Dark Knight' on July 18, 2008, the film did very well at the box office and had the largest opening weekend of any musical film in U.S. history. Like the stage musical, the film's title originates from the group's 1975 chart-topper 'Mamma Mia', and its plot is loosely based on the 1968 film Buona Sera, Mrs. Campbell. It was produced by Universal Pictures in partnership with Playtone and Littlestar. It was released on July 3, 2008, in Greece, July 10, 2008, in Australia and the United Kingdom, July 11, 2008, in Sweden, and on July 18, 2008, in the United States and Canada.Meryl Streep heads the cast of the film, playing the role of single mother Donna Sheridan.