High school students Connell and Marianne form an unlikely bond that they hide from other people. Connell is a popular football player and Marianne is lonely and private. When they attend Trinity College in Dublin, the roles switch and Marianne has a new social life while Connell shyly looks on from the outside. The two explore other people and possibilities but always return to each other. Then Marianne begins to self-destruct and Connell goes off to find meaning elsewhere, but soon they are both forced to decide how far they will go to save the other.