Mia and Frida, both in their thirties, meet each other for the first time at their parents' engagement party. Mia's father, Lasse, is about to get married to Frida's mother, Elizabeth, which will make Mia and Frida stepsisters. Mia, has not visited her father in years and arrives with her boyfriend, Tim, with whom she is about to get married. As Mia and Frida get to know one another, strong emotions begin to stir between them. Their relationship will turn everything upside down for everyone close to them with dramatic consequences.