After fighting the Master Mold on the astral plane, Xavier just made it back to his physical body outside the Sentinels‘ fortress, where he witnesses the complex sinking into the ground with his X-Men trapped inside. The Professor decides to head back for the city to examine the fallen Sentinel; he crawls to a near highway and telepathically manipulates two young men in a passing car to help him.
Inside the fortress Cyclops, Iceman, Angel and Marvel Girl have been encased in a globe of heavy gravity by the Sentinels. They all try to break out, but none of their powers are able to harm the glass wall.
In the main chamber Master Mold finished his interrogation of the Beast and now he wants Bolivar Trask to create more Sentinels. At first the scientist refuses but he obeys as the giant robot threatens to destroy the nearest city.
Back at the TV studio the fighting area has been secured by policemen as Xavier arrives. He is allowed to examine the malfunctioning Sentinel and discovers that the basic design is that of a TV set. The robot switched off, because something interfered with his receiver. Looking out of the window, the professor realizes that the disturbance must have been caused by a giant crystal on top of a crystal products warehouse. This discovery gives Xavier an idea how to end the threat of the Sentinels.
Following the Master Mold's orders some Sentinels try to put the Beast into the globe that holds the other X-Men, but as the door is opened Scott uses the chance to fire his optic beams. He causes enough confusion for the team to get out of their prison and another battle between the robots and the X-Men starts.
Again the mutants are outnumbered and about to be defeated as suddenly all attacking robots cease to function.
In the meantime Xavier had used his connections to Washington to get some helicopters to carry the giant crystal over the whole area disrupting the Sentinels' frequencies.
In the main chamber Bolivar Trask has almost finished the first Sentinel creation cycle under the watching eyes of Master Mold. Right as the first set of new robots is about to emerge Dr. Trask realizes that he can’t allow this, even if it costs his own life. Before the Master Mold is able to prevent him, the scientist destroys the ionic power source. The main chamber explodes and the whole base is about to break apart.
The X-Men save each others' lives while they get out of the huge complex. Once outside they witness the building going down in a final big explosion.
Back at the mansion in Westchester a shadow is seen aproaching the home of the X-Men.