Confusion begins when Puck, following Oberon's orders to have Demetrius fall for Helena, mistakes Lysander for Demetrius and drops the love potion meant for Demetrius into Lysander's eyes. Puck realizes his mistake, finds the sleeping Demetrius, and drops love potion in his eyes, too. The love potion makes its recipient fall in love with the first person they see. Unfortunately, both men wake to see Helena first, and both fall madly in love with her. This leads the men and the women to begin quarreling. The two young men are ready to enter into a duel as each vies for Helena. Helena and the amazed Hermia run away from each other.

To solve the problem of the two men being in love with the same woman, Puck, imitating the voices of both Demetrius and Lysander in turn, lures them away from each other and deeper into the forest. Eventually, all four young people end up back in the glade and fall asleep. At this point, Puck squeezes more love potion into Lysander's eyes, so that when he awakes, he will fall back in love with Hermia.

Puck's plan is a success, and as dawn breaks, the forest has worked its magic. Demetrius is still in love with Helena, as she has long wished. Lysander is back in love with Hermia. Puck has had some fun, and the love potion mix-up has illustrated the lunacy of love.