The noble Duke Theseus of Athens is on his way home from his invasion of Scythia, where he has won a wife, Hippolyta, and a sister-in-law, Emily. Sounds like a pretty successful trip, right? Along the way, Theseus & Co. meet a group of crying women. They beg Theseus to take vengeance on Creon, King of Thebes, because of his refusal to allow them to give their husbands' bodies a proper burial. Theseus agrees and beats Creon. In the process, he wins two noble Theban hostages, cousins Palamon and Arcite.
Theseus throws Palamon and Arcite in the slammer (a tower next to his garden), without ransom. One day in early May, Emily walks in the garden, gathering flowers. Palamon sees her from the prison window and immediately starts crushing on her. He's so smitten that he cries out. Hearing his cry, Arcite runs to his cousin. But as soon as he lays eyes on Emily, he falls for her too. The knights argue about who gets dibs on Emily. Arcite finally decides that it's a dumb argument to have; since both knights will be in prison forever, they'll just have to love Emily from afar with no hope of consummation.