Hippolyta and Theseus are getting married in 4 days.
Hermia's father, Egeus wants her to get married to Demetrius and not her lover, Lysander. Theseus gives her until the wedding to decide if she wants to marry Demetrius, become a nun, or die. She decides to run away with Lysander
Hermia and Lysander run away from Athens and try to go to Lysander's aunt's house. While they are sleeping Puck puts a flower in Lysander's eyes not knowing that that's not Demetrius.
Puck puts the flower in Demetrius' eyes and the antidote into Lysander's eyes because he accidentally fell in love with Helena when Demetrius was supposed to fall in love with Helena.
They all wake up and Lysander is in love with Hermia again and Demetrius is still under the spell and is in love with Hermia. When they wake they all believe it was all just a dream
Theseus and Hippolyta are getting married and had the other two couples get married on the same day to make a triple wedding.