In the X-Men's war room, Havok briefs them on an alien race known as the Z'Nox, creatures from the Andromeda galaxy who are a warrior race with no compassion who go across the galaxy invading and enslaving entire planets, and that their next target is planet Earth. They intend to use a Gravitational Transformer to decimate the entire planet with earthquakes and tidal waves. The X-Men are shocked by this, but are entirely skeptical that the novice members of their team could have done such extensive research. Havok tells them that they had not, that someone else had, as Jean breaks down in tears of relief at no longer having to keep the secret any more. Professor Xavier enters the room alive and well, much to the surprise of everyone else.

The Professor explains that months ago he had become aware of the coming Z'Nox invasion and he was required to go into hiding in order to prepare a suitable defense to drive them away. Visited one night by the terminally ill Changeling, Xavier agreed to allow him to impersonate the Professor while he prepared for the coming invasion. He then imparted a portion of his mental powers to both Changeling and Jean to upkeep the ruse. Things played out when Changeling sacrificed his life battling Grotesk and dying valiantly in the fight.
With his explanation complete, the Professor puts the X-Men through a rigorous training routine to prepare to be the first line of defense against the Z'Nox. When the Z'Nox activate their hidden weapon on the South Pole, SHIELD is the first to react, however the device’s defenses prove too powerful for the spy agency to get past. With the X-Men ready for battle, the Professor has them all board a rocket that he has prepared for this mission and launches them at the approaching Z'Nox planetoid. Getting past the planetoid’s defenses, they crash into one of the buildings, and upon emerging find a gigantic alien creature waiting for them inside.
As the Z'Nox weapons begin to wreak havoc across the world, the X-Men defeat the creature and burst into the Z'Nox control room and begin fighting the captains of the invasion force. While on Earth, the Professor, with Lorna's help, begin the final strike against the Z'Nox. With his mental powers, the Professor creates a giant psi-link between all the just minds on Earth and has Lorna direct his mental energies with her magnetic powers toward Death Valley on Earth.
Professor Xavier channels all of this mental power against the Z'Nox invasion fleet. He then orders Marvel Girl, Havok, and Cyclops (with Iceman's help keeping the heat level down) to channel their powers against the transmission device on the South Pole. Unable to bare the onslaught any further, the Z'Nox invasion fleet orders a full retreat and reverses course. With the mission a success, the X-Men flee the planetoid and return to Earth.

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