Puck’s mistake leads to a lovers’ quarrel.
Characters: 
Oberon

Pleased with his success at bewitching Titania, Oberon tasks Robin with fixing the mess he made with the four Athenians. 

Robin (Puck)

After giving Oberon the good news of his success with Titania, Robin must fix the mess he made with the four Athenians. 

Demetrius

Demetrius and Lysander fight over Helena, with whom they both now believe themselves to be in love, thanks to the flower’s nectar. 

Hermia

Spurned by both Demetrius and Lysander, Hermia argues with Helena, who is now the object of the two men’s affections. 

Lysander

Lysander and Demetrius fight over Helena, with whom they both now believe themselves to be in love, thanks to the flower’s nectar. 

Helena

Helena believes that Lysander and Demetrius, who both claim to be in love with her, are making fun of her, and that Hermia is in on it. 

Scene Summary: 

Puck tells Oberon the story of Bottom’s transformation and how Titania has fallen in love with him. Happy to hear of this success, Oberon asks Puck about the other plan of getting the Athenian man to fall in love with the Athenian woman. 

Just then, Demetrius and Hermia enter that part of the woods, and Puck realizes he may have made a mistake. Demetrius was already in love with Hermia, and now he seems to have finally found her in the woods and is pleading for her to love him back. But Hermia is trying to find her Lysander, and when she runs off in search of Lysander, an exhausted Demetrius decides to give up the chase for now and get some rest. 

Oberon scolds Puck for giving the love potion to the wrong Athenian man. He tells Puck to go find Helena, while Oberon puts love juice in the eyes of Demetrius. Then Puck returns with Helena and Lysander, who are unaware of his presence. Lysander is trying to convince a disbelieving Helena that he loves her. Demetrius, having been given the potion by Oberon, suddenly shows up to profess his love for Helena, too. Helena is convinced they’re both making fun of her. Then Hermia shows up, wanting to know why Lysander deserted her. He tells her he’s in love with Helena.

The four Athenian lovers argue over their muddled relationships. Lysander and Demetrius fight over Helena, and Helena and Hermia trade insults and almost come to blows. When Lysander tries to defend Helena from Hermia, Demetrius challenges him, and the two go off to fight in the woods. 

Oberon tasks Puck with cleaning up the mess he made. He tells Puck to cast a thick fog on the woods to keep the guys from killing each other, and to use his ability to imitate voices to run the men in circles until they collapse. Once they’ve fallen asleep, Puck can put the antidote in Lysander’s eyes, and he’ll fall back in love with Hermia. Demetrius will still be in love with Helena, giving us a happy ending. Meanwhile, Oberon will go and get the boy from Titania, and then give Titania the antidote to restore her true vision. 

Puck follows through on the plan, imitating Lysander and Demetrius in turn until both men are so exhausted from futilely chasing each other through the fog that they both fall asleep. Helena and Hermia appear separately and fall asleep, too. Puck puts the antidote in Lysander’s eyes.