Professor X witnesses his X-Men fail to stop El Tigre from obtaining the second part of a mystical amulet that transforms him into the mortal personification of the Mayan god Kukulc?n. Held back by a security guard under Kukulc?n's control, Cyclops is forced to use his optic blasts to destroy the guard’s gun and push him aside in order to engage his enemy. Cyclops attempts to blast Kukulc?n, however it is redirected back at him and he is knocked out.
Kukulc?n's hired mercenaries, Toloc and Ramon enter the room and attempt to take the amulet from Kukulc?n's chest so that they might sell it on the black market. The pathetic attempt is easily stopped by Kukulc?n and forces them to flee by the very power of the sun itself. With his new powers, Kukulc?n decides that he must return back to Central America where he may resume the glorious destiny of the Mayan gods. Traveling to the roof of the museum, he creates an energy sphere around himself and uses it to fly back to Central America. Having witnessed the whole ordeal, the Professor uses his mental powers to revive Angel, Beast, Iceman and Cyclops and orders them to go after Kukulc?n, leaving Ramon and Toloc behind for the police to deal with.
Meanwhile at Metro College, the Professor calls Jean to tell her what's happening with the X-Men, Jean is concerned that the Professor chose to call her on the telephone instead of contacting her telepathically, leaving her to wonder if she is still considered part of the X-Men. Her thoughts are interrupted when Ted Roberts enters the room and introduces her to another student, Calvin Rankin. Jean remembers Rankin during her encounter with him when he became the costumed criminal Mimic. When Rankin inquires if they had met before (having had his memory of his encounter with the X-Men erased) Jean keeps up the ruse, however Calvin secretly begins to doubt the girl’s claim that they have never met.
Jean soon travels to the X-Mansion where the group is briefed on the legends of Kukulc?n by the Professor. Xavier tells them that in the past when the Mayan's abused the power of Kukulc?n's amulet it caused a gigantic volcanic eruption that filled their city of molten lava. With the briefing over, Xavier orders the X-Men to travel to San Rico to stop Kukulc?n. Jean expresses concern to Scott when she hears that he was injured in battle, however Cyclops has managed to shake off the injuries he sustained battling Kukulc?n.
As the X-Men race to San Rico in their jet, Kukulc?n has returned to the region and uses his vast powers to raise a gigantic plumed serpent with a gigantic sun stone to further increase his powers. Unearthing the long lost Mayan kingdom, Kukulc?n sits upon the pyramids throne and uses his powers to enslave the people of San Rico.
The X-Men arrive in San Rico and begin traveling through the thick rain forest between them and Kukulc?n's kingdom. Along the way, the X-Men use their powers to avoid attacks from the various wild animals in the region. Their arrival does not go unnoticed, as a mystical warning signal alerts Kukulc?n of the X-Men's arrival. The group then falls through a pit and is kept at bay by an army of spear wielding natives. However, this proves to only be a minor setback as Cyclops uses his optic blast to dig them a tunnel out of danger, they then knock the natives into their own trap.
Getting past Kukulc?n's armed guards, the X-Men try to attack the powerful demi-god but find his powers are too great for them to face. When the group notices that the sun stone is the source of their power, Iceman uses his ice powers to coat it with a thick layer of ice, blocking the stone from the sun’s rays. Meanwhile, Cyclops and Angel try to keep Kukulc?n busy. During the attack, Cyclops accidentally strikes Angel with his optic beams, shaking the group’s leader because his worst nightmare has come true; he's harmed one of his friends with his optic blast. Kukulc?n then simply blasts Cyclop