A Midsummer Night's Dream opens with Theseus and Hippolyta planning their wedding, which takes place in four days. Theseus is upset because time is moving so slowly, but Hippolyta assures him the four days will quickly pass. Their relationship has not always been so loving. Theseus won Hippolyta during a battle.
While they discuss their relationship, Egeus enters with his daughter, Hermia, and her two suitors, Lysander and Demetrius. Hermia is in love with Lysander, but her father wants her to marry Demetrius. Lysander argues that he is as good of a match as Demetrius, but Egeus won't listen. Instead, he declares that if Hermia won't marry Demetrius, she will die: This is the law of Athens and his right as her father. Theseus agrees that Hermia should obey her father but offers her a third option: spending her life in a nunnery. Hermia has until the day of Theseus and Hippolyta's wedding to decide upon her fate.
Upset by Theseus' decree, Lysander comes up with a plan. He and Hermia can escape from Athens and its unjust laws by running away to his widowed aunt's house. Here he and Hermia can marry and live in peace. As they discuss their plans, Helena enters. She is in love with Demetrius and wonders how Hermia managed to capture his heart. Hermia insists she hates Demetrius. She and Lysander then tell Helena about their plan to leave Athens. In a last effort to gain Demetrius' love, Helena decides to tell him of this plot, but she doesn't receive even a "thank you" from her cold-hearted lover.
From the Duke's palace, the scene switches to the cottage of Peter Quince, a carpenter who directs a group of amateur actors in his free time. He has chosen the play "Pyramus and Thisbe" to perform for Theseus' wedding and is in the process of casting roles. Nick Bottom, the weaver, is given the leading role of Pyramus, while Francis Flute, the bellows-mender, wins the female lead, Thisbe. The remainder of the roles are assigned, and the group plans to meet the following night at the Duke's oak for a rehearsal — the same woods where Hermia and Lysander plan to meet on their flight from Athens.
The action of the play now shifts to this fairy-enchanted woods, where Puck, Oberon's joker, speaks with one of Titania's fairies. The fairy recognizes Puck as the troublemaker, Robin Goodfellow. They also discuss the argument between Titania and Oberon; Oberon is angry with Titania because she refuses to give him the Indian boy she is raising. While Puck and the fairy talk, Titania and Oberon enter from opposite ends of the stage. After criticizing each other's infidelities — Titania was supposedly in love with Theseus and Oberon with Hippolyta, among others — Titania reminds Oberon that their argument has led to chaos in the natural world. Oberon says this disaster will end if she relinquishes the Indian boy, but Titania refuses. Oberon hatches a sneaky plan to get the boy back. He sends Puck out to find a plant called love-in-idleness, the juice of which makes any person dote on the next creature he or she sees.
While Puck is out looking for this magical flower, Demetrius and Helena wander past Oberon. As usual, Demetrius insists Helena stop following him; he even vows to harm her if she doesn't leave him alone. Taking pity on Helena, Oberon instructs Puck to put some love juice in Demetrius' eyes at a moment when Helena will be the first person he sees upon waking.
Titania and her fairies are the next to enter the stage, with Oberon secretly following. When Titania falls asleep, Oberon squeezes the love juice in her eyes, hoping a wild beast will be the first creature she sees upon waking. In the meantime, Hermia and Lysander wander near Titania's bower. Lost in the woods, they decide to stop and rest until morning. Puck sees Lysander asleep and assumes he is the nasty Athenian Oberon told him about. He puts the love juice in Lysander's eyes. Still in pursuit of Demetrius, Helena wanders past and notices the sleeping Lysander. She awakens him, and he immediately falls in love with her. Cautious and heartbroken, Helena assumes Lysander is teasing her, so she runs away. Lysander follows. Hermia awakens, calling out for Lysander's help, because she has just had a nightmare in which a snake ate her heart. She dashes into the woods in search of Lysander.
Quince, Bottom, and the other actors are the next characters to meander near Titania's bower. As they rehearse "Pyramus and Thisbe," Puck secretly listens, appalled by their awful acting. Deciding Bottom is the worst in the bunch, Puck gives him an ass-head. When Bottom saunters out of the woods to deliver his lines, the other actors fly from him in fear. Bottom is unaware of the transformation and walks unworriedly through the woods. Singing as he passes her bower, Bottom awakens Titania who immediately falls in love with him.
Puck explains all of these events to Oberon, who is pleased with the way his plan has turned out. Indeed, everything seems perfect, until Demetrius and Hermia walk past, Hermia believing Demetrius has harmed Lysander, who has mysteriously disappeared. Oberon realizes that Puck has anointed the wrong Athenian with the love juice. Angry with this mistake, Oberon sends Puck in search of Helena, vowing to charm Demetrius' eyes when she appears. Now both Lysander and Demetrius are in love with Helena, adding much to Puck's amusement at the foolishness of mortals. Helena still believes they are teasing her. When Hermia honestly, and confusedly, says she knows nothing about the sudden switch in Lysander's feelings, Helena believes she is simply playing dumb: In her opinion, her three friends are laughing at her.
Before a serious fight breaks out between Demetrius and Lysander, Oberon has Puck create a fog that will keep the lovers from finding one another. While they're sleeping, Puck reverses the spell on Lysander. He also casts a spell so none of the lovers will remember what has happened in the woods. In the meantime, Oberon returns to Titania's bower in search of the Indian boy. Titania willingly releases him because she only has eyes for Bottom. Oberon's plan is now complete, and he is disgusted to see his queen in love with an ass, so he releases her from the spell.
Titania awakens and tells Oberon about her strange dream of being in love with an ass. Oberon has Puck remove the ass-head from Bottom. Now that Oberon has won the Indian boy from Titania, he is willing to forget their argument, and the two, reunited, dance off together so they can bless Theseus' marriage.
Morning has arrived and Theseus, Hippolyta, and Egeus are walking through the woods. Theseus suddenly spies the sleeping lovers and imagines they woke early to observe the rite of May. When the lovers are awakened, Demetrius confesses that he now loves Helena. Theseus decides the other lovers should be married along with him and Hippolyta. As they return to the palace, the scene shifts to Bottom. Just awakening from his dream, Bottom declares he'll have Quince write a ballad about it, called "Bottom's Dream," because it has no bottom.
Quince and the other actors haven't forgotten their missing friend, Bottom. They worry "Pyramus and Thisbe" won't be able to go on without him, which saddens them because Theseus is known for his generosity, and they might have been rewarded with a lifelong pension for their performance. As they lament this lost opportunity, Bottom suddenly returns. His friends want to hear his story, but Bottom tells them there isn't time for that: They must prepare for the play.
In the final scene, the play has come full circle, and all of the cast returns to the palace where Theseus and Hippolyta discuss the strange tale the lovers have told them about the events of the previous evening. The joyous lovers enter, and Theseus decides it is time to plan the festivities for the evening. Of all the possible performances, the play "Pyramus and Thisbe" turns out to be the most promising. Theseus is intrigued by the paradoxical summary of the play, which suggests it is both merry and tragical, tedious and brief. The players finally present their play. Hippolyta is disgusted by their pathetic acting, but Theseus argues that even the best actors create only a brief illusion; the worst must be assisted by an imaginative audience. The play ends with Puck's final speech, in which he apologizes for the weakness of the performance and promises that the next production will be better.