Mamma Mia! was one of the first of a new trend for compilation musicals, taking the hit singles of a group or band and weaving them (or sometimes forcing them) into a plotline. Mamma Mia! takes the phenomenally successful music of Swedish pop group Abba and fits the songs to two interwoven love stories. One is centred around a girl about to get married, and the other focuses on her mother who is about to confront her past. Benny Andersson and Björn Ulvaeus, the two male members of Abba who also wrote the music for the group were involved in the creation of the show, which has a book by Catherine Johnson. It opened in April 1999 at the Prince Edward Theatre in London and thanks to the melodic and lyrical brilliance of the music, it has spread as far afield as Hamburg, Toronto, Los Angeles, and Korea and is still going strong.