(An X-Men: Evolution tribute to the original five X-Men -- Cyclops, Marvel Girl, Angel, Beast and Iceman!)
Gambit sneaks into the home of Warren Worthington III and steals half an artifact. Warren tries to go after Gambit, but is telepathically assaulted by a mysterious force.
The mysterious force turns out to be Mesmero, who had hypnotized Gambit into stealing the artifact. Magneto in turn captures Mesmero and forces him to release his telepathic hold on Gambit. Magneto also leaves with the artifact. With Mastermind telepathically interrogating Mesmero, Magneto learns about Apocalypse and the keys to releasing him.
At the Institute the next morning, the students are playing a game of baseball. Inevitably, they end up using their powers in the game. Halfway through the game, Angel pays the X-Men a visit, seeking the help of Professor Xavier. It turns out that Mesmero wanted to steal the artifact which will form a spider-shaped key of some sort. Scott, Jean, Beast and Angel are setting off to stop Mesmero (who had escaped from Magneto) from stealing the other half from a museum in London. Bobby wants to tag along but they don’t think he’s serious enough to join the team.
Bobby stows away on the X-Men’s mission to London. Magneto’s Acolytes are also at the museum trying to get hold of the other half of the artifact. The X-Men meet the Acolytes and they do battle. Iceman proves himself to be quite the team player. Meanwhile, Magneto tries to stop Mesmero from getting to the artifact. While retrieving the other half from its case, the two halves join to release a huge spider-like entity.
Magneto orders his Acolytes to pursue and destroy the spider. Xavier on the other hand wants his X-Men to stop them from doing so until he can learn more about the spider’s purpose of existence. Xavier finds Mesmero and tries to force answers out of him, but Mesmero manages to escape.
While trying to stop the spider from crossing the river, Jean is flung back into the air. Cyclops catches her and breaks her fall. Iceman forms an ice bridge, allowing the X-Men to cross. However, they are too late to stop Magneto from destroying the entity. The entity was not a key, but a guardian instead. And with its demise, the second door of Apocalypse’s chamber is opened.