The play opens in a palace in Athens one hour before the wedding of Theseus, Duke of Athens, to his newly conquered Amazonian queen, Hippolyta. Their nuptials are interrupted by Egeus, an Athenian father begging help of Theseus. His daughter, Hermia, is in love with young Lysander, and wants to marry him. Egeus already bequeathed her to Demetrius, who is also in love with her. Hermia's childhood friend, Helena, is in love with Demetrius, and follows him around like a lost puppy. Theseus tells Hermia that she has until morn to decide to marry Demetrius, join a nunnery, or die.
Lysander and Hermia decide to run away together into the woods and elope near his aunt's home. They get ready to leave as they see Helena ranting about her love for Demetrius and her unhappiness that he puts her down all the time. They tell her of their plan to escape.
In a room in the carpenter Quince's house in Athens, six commoners discuss their plan to put on the play, Pyramus and Thisbe, at the Duke's wedding. Quince dispenses the roles to the players, most notably the over-dramatic weaver Bottom. He will play Pyramus, while Flute will play Thisbe.
In the woods, the sprightly fairy Puck addresses the audience with his mischievous nature. Oberon and Titania enter the woods, furious with one another over the possession of a little Indian boy. Oberon spot Demetrius running into the woods looking for Hermia, followed by a doting Helena, whom he hates. He tells Puck to find a magic flower that holds juice that when placed on sleeping eyelids, makes the person sleeping fall in love with the first creature he or she sees upon waking. He tells Puck to place it on the sleeping eyes of a man he will notice by the Athenian clothes he has on (namely Demetrius). Puck plans to obey these orders.
Oberon sees Titania and plans to play a trick on her by placing the magic juice on her eyes, as well, allowing her to fall in love with a fool.
Lysander and Hermia go to sleep, separately because they are not yet married. Puck sees them and thinks that Lysander is the man on whose eyes Oberon wants the magic juice placed. He does so. Helena runs into the woods at the same spot, sees Lysander, wakes him for fear of death, and Lysander falls in love with her. He leaves the sleeping Hermia to follow Helena and win her heart.
The six players rehearse in the woods. Puck plays a trick on Bottom by transforming his head into that of a donkey's. The rest of the men are frightened off. Bottom is unaware of his appearance. Titania awakens, sees Bottom, and falls in love. She and her fairies adorn him with flowers, attention, and "love."
Demetrius follows a lonely and distressed Hermia through the woods looking for Lysander. She blames him for Lysander's disappearance. They bicker as Oberon and Puck watch, realizing that Puck placed the juice in the wrong's Athenian's eyes. They sleep and Oberon squeezes the juice into Demetrius's eyes for Helena. He awakens, sees Helena, and falls in love. Lysander and Demetrius now fight for Helena, where they used to fight for Hermia. Hermia is now cast aside and cursed by the two men. Helena believes they are all playing a cruel joke on her. Hermia attacks Helena for stealing her lover and the insults fly on both parties' end. The two women then run away enraged.
Oberon reprimands Puck for his negligence and vows to make peace of the chaos. Puck tricks the two men into falling asleep and places the juice back in Lysander's eyes. He gets all four lovers to sleep in one location and says that in the morning, both couples will be happy and all will be well.
Titania still tends to Bottom, but they get tired and lay down to nap. Oberon, pleased with his handiwork, places the juice back in her eyes and allows her to return to her normal state. She awakens and returns to Oberon, thinking it was all a dream. Bottom's head returns to human status and he returns to Athens finding the players at Quince's house worried. They prepare to perform the play at the Duke's wedding night.
Egeus, Theseus, and Hippolyta are on a hunting trip in the woods and spot the four lovers asleep together. They are shocked at the amiability between the four, but welcome the new couples.
The three happy couples, Theseus and Hippolyta, Lysander and Hermia, and Demetrius and Helena return to the palace for a triple wedding. The play concludes with a hysterical presentation of Pyramus and Thisbe by the six players and a fantastical closing by Titania, Oberon, and Puck.