The team — Mr. Fantastic, Invisible Woman, Human Torch and The Thing — follow the villain Diablo through a mystic portal he opens in Manhattan, transporting them to ancient Milan. Their mission: rescue captives including Enid Richards, Rachel Grimm and Dr. Storm. The F.F. disguises themselves as a traveling carnival to infiltrate Diablo's stronghold. During the attempt, water-based duplicates of the Fantastic Four are unleashed by ancient alchemists, catching them off guard. In the castle, Diablo revives Enid Richards and attempts to teleport outside, threatening Earth’s destruction. The Thing confronts Diablo — but Diablo transforms him into fragile ceramic stone, causing his body to crumble. As Diablo advances his plan for immortality and Earth’s destruction, the surviving members struggle to stop him.