Many people are descending on the Greek island of Kalokairi, specifically to the rustic resort hotel called the "Villa Donna", owned and operated by single mother Donna Sheridan (Meryl Streep), for the wedding of Donna's twenty-year-old daughter Sophie (Amanda Seyfried) to her boyfriend Sky (Dominic Cooper). Three of the people who are coming to the wedding, but Donna doesn't know, are coming are architect Sam Carmichael (Pierce Brosnan), banker Harry Bright (Colin Firth), and sailor Bill Anderson (Stellan Skarsgård), none of whom Donna has seen in over twenty years. Unbeknownst to her, Sophie invited the three, since she, who gleaned as much from secretly reading Donna's diary, knows that the three were men involved in her mother's life when she was conceived, and thus surmises that one of them must be her father. She wants that man to walk her down the aisle and give her away. With help from her bridesmaids Lisa (Rachel McDowell) and Ali (Ashley Lilley), Sophie tries to figure out which is her father. When Donna sees the three men, she, with the help of her best friends and former singing partners Rosie Mulligan (Dame Julie Walters) and Tanya Wilkinson (Christine Baranski), also tries to figure out what she will do with these three. Meanwhile, the men, who didn't know each other, or of each other, before arriving on the island, quickly surmise the reason why they were invited, each believing he is indeed Sophie's father. As complications ensue from the misunderstandings, Sophie and Sky's wedding and relationship may be jeopardized, while, finding what is truly in their hearts, many may discover the course of true love.