All Might, Izuku, and Melissa believe they've rescued David from the clutches of the villains. David only has a few moments with his loved ones before Wolfram abruptly attacks All Might with an iron pillar.
Wolfram equips David's prized invention, the Quirk Amplification Device. This gives Wolfram an enormous power boost and he uses his enhanced Quirk to manipulate metal from the uppermost floors of the central tower. He destroys the tower's rooftop, transforming into a scrap metal hell and encases David inside it.
All Might recover from the attack and coughs up some blood. This lets him know that his muscular form is reaching its limit. The No. 1 Hero tries finishing the fight before it begins with a Texas Smash. However, Wolfram's Quirk has improved and he uses it to create a giant metal wall that blocks All Might's punch, much to the heroes surprise.
Wolfram pushes All Might back and further augments the entire top section of the tower, placing himself on an iron throne where he can freely manipulate the warped environment. Wolfram commends David Shield for his splendid invention, admitting that he can feel his Quirk's power skyrocketing. He believes the best way to get a great price for this device is by using it to destroy the Symbol of Peace. 
All Might leaps after the metal villain, only to be met by an onslaught of metal chunks trying to crush him. He's able to dodge the first few, but Wolfram pins him down with little effort. The impact of the attack destroys Melissa's footing. Izuku saves her as he looks on at All Might's struggle. Wolfram follows up with more iron pillars that put pressure on All Might and force Izuku to evade.
Wolfram sends another metallic barrage to finish of All Might, but they're frozen mid-attack. Katsuki flies into the air and unleashes his explosions at maximum firepower. Wolfram is able to block the explosions with an iron wall and Katsuki tells All Might not to lose. Shoto and the other students arrive at the battle and Izuku is overjoyed to see them.
Tenya and Eijiro fight to keep the metal chunks away from their friends. Inspired by his student's passion, goes beyond his limits and breaks through the iron structures that threaten to crush him. All Might chants "Plus Ultra" as he soars toward Wolfram, dodging and breaking through metal assaults at every turn. He perseveres and breaks through Wolfram's defense with Carolina Smash!
Just when things look like their in All Might's favor, Wolfram surprises everyone. He restrains All Might with wires, chokes him, and squeezes his weak point using a surprise Muscle Augmentation Quirk. All Might' can't believe Wolfram has more than One Quirk and makes a quick connection. Wolfram confirms All Might's worst fears and says that All For One gave him this new power just to fight the Symbol of Peace.
Wolfram pushes All Might against the wires using a metal pillar and then crushes him using giant cubes. He tries finishing him off using giant metal spikes, but Izuku saves him in time using a Full Gauntlet Detroit Smash to break the metal apart and send it flying back at the villain. All Might and Izuku recover and the sensei scolds his student for being reckless with his body. Izuku replies that he has to help someone when they're in need. Proud, All Might admits he's in trouble and asks young Deku to help him finish the job.
Deku arms his Full Cowl and bets his chances on Full Gauntlet allowing him to go all out. He follows his master as they rush into battle, ready to face Wolfram's iron might. Still recovering from Izuku's earlier attack, Wolfram tries to stop the two heroes. First, he combines scraps into giant iron cubes and launches them, but Katsuki blasts them apart using his super explosions. All Might and Deku continue on and are met by an ambush of descending metal pillars. Shoto refuses to let the villain stop them and creates an ice shield for them to block the attack.
Desperate, Wolfram sends iron pills out to destroy more of the rooftop. This destroys almost everyone's footing, but All Might and Deku continue forward at high speeds. They traverse the terraformed landscape, using One For All to dodge and smash through iron chunks. Deku goes beyond his limits and even smashes clean through one of the iron pillars with a powerful kick.
With one final last-ditch effort, Wolfram compiles dozens of giant iron cubes and fuses them to create a gargantuan steel cube. He threatens to crush the entire tower with his new weapon of mass destruction. All Might and his successor chant what it means to be a hero and prepare a unison Super Move to counterattack. Wolfram sends the gigantic cube at his foes for his final attack. Deku and All Might work together to break through the cube with incredible ferocity using a Double Detroit Smash!
All of the others shout and encourage the duo as they soar to victory. Wolfram tries to defend himself by encasing his body in an iron defense. Izuku and All Might tap into all of One For All's power and beyond, going Plus Ultra together one last time to crush Wolfram and obliterate his iron fortress. Deku breaks his Full Gauntlet, but Wolfram is defeated once and for all. 
Wolfram and his men are left defeated and the Quirk Amplification Device is completely destroyed. All of the young heroes are okay and they look on, confident that they've won the day.
Melissa finds Izuku recovering under a pile of junk. She thanks him for saving the day, but he believes that she was just as much of a hero as he was. All Might checks on David and tells him he's come to rescue him. Izuku tells Melissa that Full Gauntlet saved him over and over today, and apologizes for breaking it.
David apologizes to All Might for the incident, stating that he was afraid the Symbol of Peace would fade. Now he realizes that young Izuku will become the next No.1 Hero. He thanks All Might for saving him but All Might gives all the credit to Izuku and Melissa, the two heroes of the day. David believes he can see the same light in Izuku that he does in All Might, the light of a hero.