You know ABBA, right? The 1970s pop group, beloved worldwide, wrote and recorded the catchiest tunes this side of Lennon and McCartney? The Swedish foursome were all over the airwaves, and still are, and their body of work was the springboard that launched the musical Mamma Mia! The Timber Lake Playhouse is running its spectacular production of the show now. Grab a seat before they're gone.