Obey thy father, Egeus, and marry Demetrius, else you shall face death or live in a nunnery.
Theseus, King of Athens
I am going to run away with Lysander.
I wish Demetrius would love me.
And for her sake I will not part with him.
Give me that boy.
Ahh, how beautiful Helena is.
Why do you mock me? You love Helena.
In Athens, Hermia and Lysander love each other, but Hermia's father Egeus wants Hermia to marry Demetrius. In accordance to Athenian law, Theseus tells Hermia to obey her father or be punished. Helena is Demetrius' ex and still loves him.
You're an ass, Bottom!
*confused and sad that his friends ran away*
This man is so beautiful! I love him!
Oberon is fighting with Titania for the (king and queen fairies) possession of a Indian boy. Meanwhile, Oberon tells his servant, Puck, to give a love potion to Titania and to Demetrius that makes those infected fall in love with the next person they see. He plans to make Demetrius love Helena.
THIS IS A DISASTER! FIX IT.
Puck completes his task, but makes the mistake of giving the potion to Lysander instead of Demetrius. Lysander then fell in love with Helena.
A grand success.
Puck also happens to come across a group of actors. He transforms the face of Bottom, one of the actors, into a donkey. Titania, who has been infected by Puck's love potion, sees Bottom and falls in love with him.
Nothing happened as Oberon wanted it. He demands that Puck fix everything.
Puck fixes the whole situation so that everyone marries who they want to (except for Demetrius, who loves Helena due to love juice). Theseus and Hippolyta (queen of the Amazons) who is engaged to him find everyone and bring them back for a wedding of three couples in Athens.