At Sophie's (Amanda Seyfried) wedding it all comes out. Donna (Meryl Streep) finds out it was Sophie who invited Sam (Pierce Brosnan), Bill (Stellan Skarsgård) and Harry (Colin Firth), and the three men find out that each of them might be Sophie's Father.
Sam, Bill and Harry decides that if Sophie really wants to know the truth they can find it out, but that each would be happy being a third of her father and she agrees. She also decides not to marry Sky (Dominic Cooper) and instead wants to travel the world together.
Sam marries Donna.
Harry finds a boyfriend on the island.
Bill ends up with Rosie (Julie Walters).