Dec. 21 (UPI) -- The Mamma Mia! sequel released a first trailer Thursday that explores Donna Sheridan's youth.
"Your mother was the bravest person we ever knew," Rosie says. "Let me tell you how she did it, all on her own."
Flashbacks show young Donna (Lily James) and Sophie's three possible dads, Sam (Jeremy Irvine), Bill (Josh Dylan) and Harry (Hugh Skinner). The trio were played in the first film by Pierce Brosnan, Stellan Skarsgard and Colin Firth, who return for the sequel.
The original Mamma Mia! is based on the musical of the same name and opened in theaters in June 2008. The sequel, which also features songs from ABBA, opens July 20, 2018.