On a small Greek island, Sophie dreams of a perfect wedding — one which includes her father giving her away. The problem? Sophie doesn’t know who he is! Her mother Donna, the former lead singer of the 1970s pop group Donna and the Dynamos, refuses to talk about the past, so Sophie decides to take matters into her own hands.

Sneaking a peek in her mother’s old diaries, she discovers three possible fathers: Sam, Bill, and Harry. She secretly invites all three to the wedding, convinced that she’ll know her father when she sees him. But when all three turn up, it may not be as clear as she thought!