Puck tells Oberon of his exploits with Bottom and Titania, and Oberon is delighted. He then tells of putting the love-juice in the Athenian's eye, but when Demetrius and Hermia enter, Puck realizes that Demetrius is not the same man.
Hermia is still looking for Lysander, and fears that Demetrius may have killed him, but Demetrius denies that he has done Lysander any harm. Hermia exits, hoping that she never has to see Demetrius again. Demetrius sees no point in following her while she so angry, and he lies down to rest and sleep.
Oberon and Puck come forward, and Oberon realizes the mistake Puck has made. In order to correct it, he sends Puck off to fetch Helena, and squeezes the juice onto Demetrius's eyelids. Puck returns with news that Helena is near. Oberon and Puck stand aside to watch how their plot unfolds.
Lysander and Helena enter. Lysander swears that his love for her is genuine. Helena does not believe him; has he deserted Hermia so easily?
Demetrius awakes, and the first person he sees is Helena. He falls immediately in love with her and praises her in extravagant terms. Helena can only conclude that they are both making fun of her, and that they really hate her. She says they both really love Hermia, and have joined forces for the purpose of mocking her. Lysander agrees that Demetrius must be mocking Helena, for he is in love with Hermia. He says he is willing to give up Hermia and let Demetrius have her. Demetrius replies that Lysander can keep Hermia; he, Demetrius, is no longer in love with her, if he ever was. Now he loves Helena.
Hermia enters. She asks Lysander why he deserted her. He replies that his love for Helena took him away, and now he hates Hermia. Hermia cannot believe her ears, while Helena concludes that Hermia is part of the plot to humiliate her. She turns on Hermia and berates her. Has she forgotten the close friendship that they shared? Hermia is amazed at her friend's words. She denies the she is scorning Helena; it seems to her that it is the other way round. Helena, unconvinced, questions her further, but still Hermia does not understand. For her part, Helena does not believe Hermia's protestations of ignorance.
The four young people then quarrel bitterly. Lysander swears he really does love Helena; Demetrius says that he loves her much more than Lysander does. Lysander challenges him to fight, and Demetrius belittles him. Hermia attempts to find out what is going on, but Lysander pushes her away and insults her. She is bewildered. Lysander repeats that he hates her and loves Helena. This makes Hermia turn on her former friend, whom she believes has stolen her lover away. Helena, who still believes there is a plot to humiliate her, responds with insults. Hermia becomes so angry she threatens to scratch Helena's eyes. Helena appeals to the men for protection, and then explains her part in the situation: all she did was tell Demetrius that Hermia and Lysander were going to the wood that night. She did not try to take Lysander from Hermia. Now she promises to go back to Athens; she follow Demetrius and the others no further.
Hermia does not believe her, and Helena hits back with insults, calling Hermia malicious. Hermia tries to attack her, but Lysander restrains her and tells her to go. He insults her too.
Lysander and Demetrius exit, planning to fight a duel. Hermia blames Helena for the situation, and Helena runs away. Hermia is left to express her bewilderment and confusion.
Oberon and Puck come forward. Oberon is annoyed by Puck's mistake, but Puck has enjoyed watching the resulting mix-up. Oberon tells Puck to veil everything with a fog, to make sure that Demetrius and Lysander do not come into contact with each other. When they get tired of searching and go to sleep, Puck is to put a herb into Lysander's eye. The herb takes away all error, and when Lysander awakes, everything he has just experienced will seem like a dream. Meanwhile, Oberon plans to go to Titania and beg her for the changeling boy. When he has the boy, he will release Titania from the spell. Puck points out that this must all be done quickly, because morning approaches. Oberon accepts this, although he says that they are not like ghosts who must return to churchyards at dawn.
Puck then confuses Lysander and Demetrius by calling their names and leading them away from each other. Tiring, Lysander lies down and sleeps, and shortly after that, so does Demetrius.
Helena enters. She too is weary and lies down to sleep. As Puck watches over them, Hermia arrives also. She is exhausted and like the three others, lies down to sleep. Puck squeezes the herb on Lysander's eyelids, saying that when he wakes up, all will be well.
The theme of the irrationality of love finds its full _expression in this scene, with its multiple confusions and switching of affections. It should be noted, however, that it is the male characters, Lysander and Demetrius, who change their affections; Hermia and Helena remain constant throughout.
The theme also shows the extent to which the humans are helpless in the face of the machinations of the fairy world. A psychoanalytic interpretation might suggest that the lovers are actually victims of their own unconscious desires.
Oberon emerges from this scene as not only a powerful spirit but a benevolent one too, since he makes efforts to sort out the love tangle and ensures through Puck that Demetrius and Lysander do each other no harm. His darker side is revealed through the ruthless way he deals with Titania.