Claude Frollo is attempting alchemy, but his thoughts of Esmeralda, a Roma dancer, hinder his concentration.

In the Paris streets is the poet Gringoire, who also pines for Esmeralda, and laments his dilemma through poetry.

Gringoire is chased by faux cripples into the Court of Miracles, the den of beggars and thieves.

Frollo refuses to testify at the trial, using the false excuse of not wanting to disgrace the church.

Quasimodo pours his heart out to Esmeralda, and she begins to pity him, apologizing for "judging (him) ugly because of (his) face".

Enraged townspeople then attack the cathedral, wanting to hang Esmeralda, but Quasimodo defends her and the church.

Down below, Phoebus makes his way through the crowd: the people are amazed to see that he is alive, he proves Esmeralda's innocence, saying that it was Frollo who had stabbed him and the gypsy "has commuted no sin in her entire life, except to be born beautiful".