Set in the year 1998, on the Greek island of Kalokairi, bride-to-be Sophie Sheridan reveals to her bridesmaids that she has secretly invited three men to the wedding, each one possibly her biological father: Sam Carmichael, Bill Anderson, and Harry Bright. She is hopeful that she will learn who her true father is so he can walk her down the aisle in her marriage to Sky Rymand. Meanwhile, Sophie's mother, Donna Sheridan reunites with her best-friends and former bandmates of Donna and the Dynamos, the wisecracking author Rosie Mulligan and the glamorous, three-time-divorcee Tanya Chesham-Leigh.