Four days before Theseus, the Duke of Athens, and Hippolyta, Queen of the Amazons, are to be married, Egeus asks Theseus to decide a disagreement between him and his daughter Hermia. Egeus wishes Hermia to marry Demetrius, but Hermia is loves and is loved by Lysander. Demetrius loves Hermia, but used to love Hermias friend Helena, who still loves Demetrius. Egeus asks Theseus to force Hermia to marry Demetrius, since the law of Athens allows a father to dispose of his daughter as he will. Theseus decides that before the next new moon, the day of his and Hippolytas wedding, Hermia must either marry Demetrius as her father wills, or live out her life in a nunnery. Lysander and Hermia discuss what to do, and decide to elope, arranging to meet in the forest the next night. Helena arrives, and the two lovers tell her of their plan. Helena decides to tell Demetrius.
A group of craftsmen gather to rehearse a play they plan to perform in honour of Theseus wedding.
Puck meets a fairy who is attendant to the fairy queen, Titania, and they talk about Titania and her king Oberons quarrel. Titania has taken a lovely boy, a changling for her attendant. Oberon is jealous, and would like the boy for himself. After this exposition, Titania and Oberon themselves meet, and quarrel.