An independent, single mother who owns a small hotel on an idyllic Greek island, Donna is about to let go of Sophie, the spirited daughter she's raised alone. For Sophie's wedding, Donna has invited her two lifelong best girlfriends--practical and no-nonsense Rosie and wealthy, multi-divorcee Tanya--from her one-time backing band, Donna and the Dynamos. But, Sophie has secretly invited three guests of her own.