Complex sentence: Frollo returns to Notre Dame later that night and realizing that Quasimodo helped Esmeralda escape, bluffs that he knows about the Court of Miracles and that he intends to attack at dawn.
Split into simpler sentences: Frollo returns to Notre Dame later that night and realizes that Quasimodo helped Esmeralda escape. He bluffs to Quasimodo saying that he knows about the Court of Miracles and that he intends to attack at dawn.