A newscaster is reporting how anti-mutant riots have occurred throughout dozens of cities in America over the kidnapping of Senator Robert Kelly. Professor X says that they need to find Kelly before an anti-mutant fever consumes the nation; as they already know that Magneto is the culprit, Cerebro will be of great assistance.
In a shipwreck, Magneto is holding Robert Kelly hostage. Magneto tells him that they both believe mutants and humans can't live peacefully, that a war between the two is inevitable, and that Kelly's assassination will serve as a catalyst. As he's about to kill Kelly, Sentinels tear through the roof and grab the Senator - the Sentinels are also new and improved: they're made of plastic rather than metal, rendering Magneto's powers nearly useless. Magneto attempts to fight them off using the metal of the shipwreck, but he's punched into submission and buried in the rubble.
The X-Men, picking up signals from Cerebro, arrive to the shipwreck in the Blackbird. They find the shipwreck abandoned, as well torn parts of Sentinels, and Magneto hurt and without his helmet.
Kelly is brought to a secret lab of robotic scientist, Bolivar Trask, who wants a presidential authorization for using Sentinels in charge of controlling mutants. Trask orders a newly-built Sentinel to bring Kelly back to his campaign headquarters, but it refuses. Trask then turns to a rebuilt Master Mold, who informs Trask that the Sentinel is not defective and is following his orders. Master Mold wants to replace the brains of world politicians, including Senator Kelly's, with a computer.
Back at the X-Mansion, the X-Men realize they need to attack the Sentinels before they get too strong but don't know where to start. Storm points out that, on Genosha Gambit saw the face of the man in charge of the Sentinels and Charles decides to use Cerebro to enter Gambit's mind to discover the man is Henry Peter Gyrich. The X-Men ambush Gyrich, who was also the target of an assassination, and he flees into a building. Wolverine, however, catches up to him and pins him to the ground; the X-Men interrogate him, while also overhearing Trask on the phone saying that the Sentinels are not only out of control but also seeking to replace the brains of world leaders. Scott says he needs to help them as the Sentinels are now a threat to the world, but Gyrich says that thousands of Sentinels have been created already.
The X-Men return to the mansion, where Charles insists that Kelly must be rescued or else there will be a civil war; some, such as Gambit, believe to attempt a rescue would be suicidal. Magneto, still recovering, enters the room and agrees, telling Charles his dream of peace between humans and mutants was foolish, and that if they try to rescue Kelly, the team will be throwing their lives away. While some members are still reluctant, (Rogue, Gambit, and Wolverine) ultimately the X-Men decide to take the Blackbird to rescue Kelly, while Magneto quietly says that the bravest are always the first to die.
Following Gyrich's tips, the X-Men arrive at Trask's hideout where they split up: Jean, Gambit, Scott and Wolverine infiltrate the factory while setting up one of Gambit's exploding cards as a bait to draw the Sentinels while Professor X (piloting the Blackbird), Jubilee, Storm and Rogue distract the Sentinels. They then destroy dozens of robots but with hundreds of Sentinels pouring out of the factory they're quickly overwhelmed, and the Blackbird is damaged and starts to fall. However, Magneto has followed them and uses his powers to stabilize the jet, preventing the Professor's death.
Gambit and Wolverine are ambushed by Sentinels and Wolverine attempts to make a sacrifice by putting Gambit outside the room while he fights them off. While the mutant manages to defeat dozens, more Sentinels keep pouring in and Gambit has to rescue them. Meanwhile, Trask is arguing with Master Mold, saying that he was designed to protect humans from mutants and thus he must protect humans from themselves. Jean and Scott attempt to rescue Kelly but are detected. However, a horrified Trask, realizing he's created a monster, turns a machine with Frickin' Laser Beams to a propane mane, distracting Master Mold long enough to allow them escape at the apparent cost of Trask's life to atone for his mistake of building Master Mold in the first place.
Outside the Sentinels realize their master is in danger and return to the factory, leading to their own destruction when the factory explodes. Scott splits off from Jean and Kelly, who escape outside, to find Wolverine and Gambit, who succeeded in defeating the Sentinels. Using his Eye Beams, Scott digs a tunnel for them to outside, but when they arrive, Master Mold appears from the mountain, refusing to accept defeat so long as it was still functioning. Professor X pilots the Blackbird, protected by Magneto's magnetic fields and loaded with tons of explosives, into the giant robot and escapes through the ejection seat before the Blackbird hits Master Mold and the explosives detonate, destroying both the Blackbird and the Sentinel boss. Magneto tells him that they're even and that they shall meet again before taking his leave.
Later, at a press conference, Kelly reiterates that mutants are human beings, and that they should not forget that in attempting to control mutants that abuse their powers, they should not oppress mutants that use their powers for the good of humanity. With Kelly's influence, Beast is set free and later, Scott asks Jean to marry him, which she accepts.
This episode provides examples of:
- A.I. Is a Crapshoot: Master Mold is merely following its programming of protecting humans from mutants, but it has realized that mutants are humans, thus coming to the conclusion that its goal is to protect humans from themselves.
- Armor-Piercing Response: Trask is left stammering after Master Mold's response to Trask stating Sentinels were supposed to protect humans from mutants.Master Mold: That is not logical. Mutants are humans.
- Assimilation Plot: Master Mold plots to put the most important world leaders under its control by replacing their brains with computers
- Big Damn Heroes: Magneto saves Charles' life when the Blackbird starts spiraling into the ground after being damaged by the Sentinels.
- Big "SHUT UP!":Kelly: Please, I have a family, children!
Magneto: BE QUIET! - Big "WHAT?!": Senator Kelly's memorable reaction to Master Mold wanting to replace his brain with a computer.
- Bittersweet Ending: The X-Men save Senator Kelly, who sees that mutants aren't all bad, and changes for the better during his campaign for president; Master Mold is destroyed, Beast is released from jail, and Scott asks Jean to marry him. However, little do the X-Men know that there is a new threat who is after Scott and Jean...
- The Bus Came Back: With this episode, Beast is freed from federal custody and rejoins the team full-time.
- The Cameo: Ghost Rider appears among Gambit's memories.
- Cliffhanger: As Scott and Jean muse about their future together, they're watched by someone sinister.
- Crazy-Prepared: An entire line of Sentinels was made out of plastics and on standby in case Magneto ever attacked again.
- Curb-Stomp Battle: The Sentinels made of plastics deliver one to Magneto. He puts up a good fight at first, but he's overwhelmed by superior numbers.
- Early-Bird Cameo: Bella Donna appears among Gambit's memories. She'll appear in Season 2's "X-Ternally Yours" as an antagonist.
- Elemental Rock-Paper-Scissors: The Sentinels sent to rescue Kelly are made of plastic, and as such the Magnetism Manipulation of Magneto cannot affect them.
- Enemy Mine: Magneto teams up with the X-Men against the Sentinels and helps Xavier destroy Master Mold.
- Everyone Has Standards: Gambit is the most vocally opposed to Xavier saying they have to rescue Kelly, but he is openly angry over Magneto denouncing Xavier as a fool.
- Fantastic Plastic: When Magneto is confronted by a Sentinel, which is a gigantic android designed to hunt down mutants, the villain smugly proclaims that no robots can resist the master of magnetism, but the machine counters by explaining that it's made entirely of plastic.
- Friendly Enemy: Magneto pulls off his Villainous Rescue while asking, "Did you think I would let you die alone, Xavier?"
- Friendship Moment: When Cyclops says they have to go rescue Kelly, Wolverine is the first one to voice support.
- Government Agency of Fiction: Gyrich works for the Federal Security Agency.
- Heel–Face Turn: Senator Kelly learns the error of his ways and becomes a supporter of peaceful mutant-human coexistence. His first good deed is arranging the release of Beast.
- Hoist by His Own Petard: Bolivar Trask created the Sentinels and Master Mold out of a bigoted fear of mutants and programmed them to protect humans. Because Master Mold is capable of understanding that mutants are human beings too, it interpreted Trask's programming to mean humanity must be protected from itself and thus the Sentinels turn against their masters.
- In Spite of a Nail: With Senator Kelly's assassination, Master Mold's prime directive would be changed to the extermination of all mutants. Preventing this assassination gives Master Mold the time to develop his logical conclusion: endangering humans and mutants alike.
- Jerkass Has a Point: Gambit is the last holdout in rescuing Senator Kelly, much to the disapproval of Rogue and others. However, it was only mere hours before that his friends accused him of assassinating said senator and causing a Bad Future. No wonder why he's reluctant in joining his teammates on a suicide mission.
- Jerk with a Heart of Gold:Wolverine: Sit down, kid. You're not goin'.
Jubilee: I'm not a kid anymore! I'm one of you, one of the X-Men, and it means more to me than anything in the world!
Wolverine: Yeah. That's what it means to me, too. - Left for Dead: By the time the X-Men arrive at the shipwreck, they find an injured Magneto buried under rubble.
- Logic Bomb: What causes Master Mold to rebel is it has come to the realization that mutants are humans too, and as such, he must protect humans from themselves.
- Makes Us Even: Magneto reasons that saving Xavier's life during the final fight repays the debt of receiving medical attention at the mansion.
- Motive Rant: Kelly saying he has a family prompts one.Magneto: When I was a boy, I saw men executed. Women and children. Each night I swore to myself, "Never again." But we must prevail. Goodbye, Senator. Mutant liberation begins!
- My God, What Have I Done?: Trask's reaction to Master Mold's plan.
- No One Gets Left Behind:Cyclops: I'm going after Wolverine and Gambit. I'm not leaving anyone behind. Not this time.
- Noodle Incident: Gambit once had an encounter with Ghost Rider.
- No-Sell: Magneto learns the hard way that his magnetic powers are useless against the Sentinels.
- "Not So Different" Remark: Magneto points out that he and Kelly both believe humans and mutants can't coexist peacefully.
- Not Worth Killing: Master Mold shoots Cyclops, only stunning him - after concluding that he is not a personal threat to him or his plan.
- Outrun the Fireball: Played with. Jean, Scott, and Kelly manage to outrun the fireball for some time, but they are forced to use telekinetic shields to protect themselves because the fireball runs too fast. Somehow, Trask also manages to escape from the explosion.
- Ramming Always Works: Having foreseen Master Mold's Not Quite Dead moment, Xavier finishes things by ramming the Blackbird (also full of explosives) into him.
- "The Reason You Suck" Speech: Magneto delivers one to Xavier."You've lost, Xavier. Admit it. Peace between mutants and normal humans is only a dream... your foolish dream. If you try to rescue Kelly, you'll be throwing your lives away for nothing."
- Save the Villain: Finding Magneto unconscious and bleeding at the shipwreck, the X-Men take him back to the mansion and put him in the infirmary.
- Say My Name: After seeing what his creator intends for the propane mane, Master Mold shouts, "TRASK!"
- Series Fauxnale: The episode has a number of arcs cleanly tied up in case the series wasn't renewed. The Sentinels are defeated, Beast is released from prison, Senator Kelly stops his anti-mutant rhetoric, Magneto and Xavier form a truce, Rogue and Gambit share an Indirect Kiss, and Cyclops asks Jean to marry him.
- Shout-Out to Shakespeare: On his release, Beast quotes Macbeth: "To-morrow, and to-morrow, and to-morrow, creeps in this petty pace from day to day…." He claims it represents "the struggle of the oppressed," which is an interesting interpretation. note
- Silly Rabbit, Idealism Is for Kids!: Magneto's opinion of peace between humans and mutants.
- Sinister Surveillance: Pun aside, Sinister surveils Scott and Jean as they celebrate their wedding proposal.
- Tsundere: Rogue, when she sees Gambit survived the explosion, gives him a kiss (blocked by her gloved hand, of course) and then says she hates him. Gambit remarks he doesn't understand her at all as she hugs him.
- Turned Against Their Masters: Master Mold has gained sentience and intends to take over the world.
- Villainous Rescue: During the final fight, Xavier pilots the Blackbird and gets shot down. Right before hitting the ground, Magneto stops the plane and prevents the impact.
- Waving Signs Around: Protestors wave anti-mutant signs in the news to protest Kelly's kidnapping.
- We Will Meet Again: What Magneto tells Xavier before departing.
- You Are What You Hate: Trask says he created the Sentinels to protect humans against mutants. Master Mold reminds him that mutants are human.
- You Fool!: Master Mold's reaction to Cyclops and Jean attempting to rescue Kelly.
