The expansive I-Expo event is being held on I-Island. Heroes, scientists, and civilians come together to celebrate technological advancements in the hero world. Popular names like the No. 1 Hero All Might and Nobel Peace Prize Winner Professor David Shield are in attendance.
This attracts the attention of other, more devious entities. Wolfram and his gang secretly infiltrate the I-Expo with the help of a mysterious informant. During the early access event's reception party on the first night of the expo, Wolfram's minions take control of the security system in the central tower. This turns I-Island's security programs, that which rival Tartarus, against the heroes and civilians present.
Wolfram abruptly disrupts the party in person, using restraining devices to quickly subdue all the heroes. He claims all the inhabitants of I-Island as his hostages. The villain promises not to take anyone's life as long as his demands are met. He seeks out David and his assistant Sam before taking them away from the reception hall.
All Might can do little more than watch helplessly, bound on the floor. Luckily, his young protege and the other U.A. students attending the party haven't been caught by the villains. All Might informs them of the dire situation, and after heavy thought, the students decide to save the day. All Might is reluctant to put the students in danger, but he's proud to be their teacher and puts his faith in them. 
Swordkil escorts David Shield and his assistant Sam to the security room. The students try to use the emergency stairs to reach the 200th Floor of the tower but they run into a blockade on the 80th floor. Minoru opens another passageway that alerts Wolfram's henchmen in the security room. Wolfram orders them to use the shutter doors to trap the trespassers.
The shutter doors nearly succeed in trapping the students but Shoto freezes one of the doors and gives Tenya an opening to break through into the botanical gardens. Kyoka immediately notices the central elevator ascending and everyone decides to hide. Two Villains exit the elevator and before long they notice the students. However, the students they discover are Katsuki and Eijiro, who got lost on their way to the reception party.
The Villains quickly get hostile, but Shoto springs into action. He blocks his allies with a shield of ice and raises the others to the next floor using a pillar of ice. Shoto tells the group to continue the mission while he holds off the villains.
Shoto tells Katsuki and Eijiro about how criminals have taken over the tower. Wolfram's duo of minions breaks through Katsuki's ice. The smaller one activates his Quirk, transforming him into a purple hulking beast. Shoto sends a freezing wave at him, which the villains break through using brute strength. Katsuki lands an explosion, but the beast shrugs this off and counterattacks. Eijiro hardens himself and protects Katsuki from the blow, but gets sent flying away as a result.
Shoto warns Katsuki to dodge the next attack, a vacuum wave coming from the other villain. Katsuki evades and Shoto covers him using another wave of ice. The vacuum displaces the ice, forcing Shoto and Katsuki back to back. The villains commend the two boys on their fighting skills and ask who they are. Both Shoto and Katsuki refuse to acknowledge them, saying they don't deserve to know anything about them.
Momo uses her Quirk to create a small explosive that opens a vent on the roof. Denki convinces Minoru to climb through by promising him a harem of women after the incident is over. Minoru climbs the outer wall of the tower and enters the maintenance room through another vent and lets down the latter to help the others up to the next floor.
The brawl between U.A. students and Wolfram's minions continues on the 80th floor. Katsuki uses his explosions outmaneuver his opponent and land a few solid blows while Shoto keeps his distance and uses his signature freezing attacks. Nobu is able to wither away the ice using his Quirk, prompting Shoto to realize the villain's power grants him the ability to displace anything his vacuum touches. Growing tired of the battle, Katsuki decides to finish off Daigo with his Howitzer Impact attack.
Nobu tries to take Katsuki off guard but Shoto warns him in time. Nobu ends up displacing the sweat on Katsuki's arm, which the student confirms works like nitroglycerin. Shoto shoots his flames at Nobu, detonating the sweat and defeating him. Shoto freezes Nobu before the duo moves to check on Eijiro. Eijiro turns out to be fine and he asks for some details on the villain attack, but they're interrupted by a swarm of security sentries.
The Hacker of Wolfram's Crew tells the boss that the students are heroes in training from U.A. High and that they've been well trained. Wolfram tells his men to open the barriers up to level 130 to lead the students into a trap. The students quickly realize that this is likely the case since they haven't seen resistance for a while.
The students arrive on the 130th floor and are welcomed by dozens of robot sentries. The students decide to go with "Plan A", sending Denki ahead to electrocute the swarm of bots. The security drones deflect Denki's Indiscriminate Shock move and restrain him in his stupid form. Tenya quickly switches the plan to "B" and Momo creates smoke grenades that interfere with the robot's communications. Minoru uses his Quirk balls to trap some of the robots, but others continue rushing the students.
Tenya and Izuku step up to deal with the robots themselves. Izuku arms his Full Gauntlet and attacks with a 30% One For All smash, breaking the ranks of the drones and rescuing Denki without injuring himself. Kyoka notices reinforcements coming from the left, so the group moves to the opposite direction. The villains notice the drones' sensors are offline and Wolfram says to cut communications because he's surmised one of the students has a sensory Quirk.
The students reach more opposition on the 138th floor. Melissa warns her friends not to damage any of the servers on this floor. Tenya and Momo decide to fight with the others while Izuku, Ochaco, and Melissa go on ahead. Tenya strikes first with his Recipro Burst and Momo creates a cannon for Kyoka to fire. Minoru tries to restrain the robots and protect Denki while Momo creates soft ammo for the cannon.
Izuku notices the commotion and Ochaco reminds him to press on. The others are eventually captured by the robots but their sacrifice isn't in vain. Izuku, Melissa, and Ochaco reach the wind power generator where Melissa plans to get to the top of the tower without running into any more drones. Ochaco uses her Quirk to float Izuku and Melissa up toward the tower's peak, but more drones ambush her just after she's left alone.
Just before the drones swarm her, Katsuki appears and blasts them away with an explosion. Shoto and Eijiro quickly join him and safeguards Ochaco from the bots. A strong gust of wind blows Izuku and Melissa off course, but Shoto acts quickly and asks Katsuki to move on of the wind propellers. Shoto uses his flames to create a draft of hot wind that sends Izuku and Melissa back to the top of the tower. Izuku uses Full Gauntlet at 100% to break through the tower wall and Ochaco releases her Quirk.
Wolfram tells his men to protect the control room, ordering Swordkil to neutralize the threat himself. Wolfram exits the reception hall and heads to the control room as well. Izuku and Melissa are immediately confronted by Swordkil, who nearly knocks Izuku out of the tower. Melissa distracts Swordkil long enough for Izuku to defeat him with a single punch from Full Gauntlet.
Izuku continues to fight his way through Wolfram's henchmen until he and Melissa finally reach the top floor of the tower. They notice David and Sam in the storage room and believe the villains are holding them hostage. David manages to unlock "Block 1147" and retrieves his Quirk Amplification Device. He thanks Sam for helping with this plan but Melissa overhears them and confronts her father.
Sam explains that I-Island's sponsors confiscated David's device because it was deemed too dangerous, ruining his research. They planned to steal the research back using fake villains. Izuku and Melissa are horrified to hear the truth, but David admits to all of it. He explains that he did this to help restore All Might's power so he can continue being the Symbol of Peace. Furious, Melissa shows her father her injuries and says the U.A. students risked their lives to help her get here. Confused, David claims the villains were supposed to be actors.
Wolfram abruptly appears and reveals that the only act was pretending not to be real criminals. He immediately restrains Izuku by manipulating metal into a bonding him to a wall. The masked villain tells them not to resist and orders Sam to hand over the device. Sam betrays David, claiming that he was never paid for all his hard work. Wolfram double crosses Sam and shoots him with a gun. He tries to finish him off but David jumps in the way of the second bullet.
Melissa rushes to her dad's side but Wolfram smacks her away. The villain taunts David, telling him a villain now because of his actions. He plans on abducting David after he gets rid of his attachments. Izuku frees himself and stops Wolfram from shooting her. He tells Melissa to rescue everyone else while he goes after Professor Shield. Izuku holds off the villains long enough for Melissa to reset the security system, saving everyone on the Island.
All the Pro Heroes including All Might are released from their bonds. They quickly take out the villains and secure the reception hall. All Might gets a call from Melissa and she updates him on the dire situation. Wolfram and his two remaining henchmen try to escape with the Professor and his research via helicopter. Izuku confronts them before they take off and Wolfram barrages him with iron pillars. Wolfram turns his gun to David and instantly turns the tables on Izuku.
The helicopter takes off but Izuku refuses to give in. He leaps for the helicopter, knowing Wolfram doesn't have access to enough metal. Izuku grabs onto the helicopter and swings it off course, he tells David not to give up because Melissa is waiting for him. Wolfram nearly shoots Izuku but David interferes and the bullet only forces Izuku to let go and crash on the helipad below. Upset at his failure, Izuku screams for the villains to give the professor back. All Might makes a heroic entrance and destroys the helicopter to save David.
Their reunion is short-lived, as Wolfram uses the Quirk Amplification Device to increase his powers and takes David again, this time encasing him in a metal prison. The villain's new powers even give him enough strength to block All Might's Texas Smash. Wolfram's Quirk gets revitalized and he activates metal from all the top floors of the tower, giving him more than enough weapons to take on the heroes.
Wolfram starts to crush All Might beneath an iron onslaught, but his students come to his rescue. Shoto and Katsuki destroy the iron pillars and tell All Might to keep fighting. Inspired by his student's vigor, All Might goes beyond his limits and breaks through Wolfram's iron defenses.
All Might reaches the villain only to be restrained by a number of wires before Wolfram reveals he gained a second Quirk from All For One himself. Wolfram shifts the momentum back in his favor and nearly destroys All Might after revealing his arch nemesis was involved all along.
Izuku leaps into action and saves All Might in time with a full powered Detroit Smash. All Might thanks his young protege and asks for his help one more time to finish off the villain. Wolfram tries to crush them with giant iron cubes and pillars, but Shoto and Katsuki use their powers to keep the path open for their allies. All Might and Izuku use the break neck speed and awesome power granted to them by One For All to break through Wolfram's scrap metal barrage. He tries one last ditch effort to stop them, launching a giant metal cube that threatens to crush the entire tower.
All Might and Izuku combine their powers into a Double Detroit Smash that breaks even Wolfram's strongest attack. Everyone cheers them on as they deliver the final blow in perfect "Plus Ultra" fashion. Izuku sacrifices Full Gauntlet to put an end to Wolfram's tyranny once and for all. 
Professor Shield is freed from his prison and notices Izuku has the same light as All Might did in his young age. Wolfram is defeated and the Quirk Amplification Device completely destroyed. Toshinori confronts his friend, David, claiming he understands everything he did for the sake of the Symbol of Peace. David now realizes that Izuku will continue to carry the torch and the future has nothing to be afraid of.
Melissa thanks Izuku for saving everyone, but he replies that it was all thanks to Melissa's help as well. He apologizes for breaking Full Gauntlet and the others check up on them. All Might and David continue talking about the two heroes who saved the day. They are the future, Melissa will take the professors place and Izuku will succeed All Might. David can see the same light within Izuku's heart that All Might has, the light of a hero.
Wolfram and his men are arrested. David is admitted to the hospital where Melissa visits him. Izuku and All Might leave the island together after conflicts end.
- Katsuki & Shoto vs. Daigo & Nobu
- U.A. Students vs. I-Island Security Bots
- Deku vs. Swordkil
- Deku vs. Wolfram
- All Might & Deku vs. Wolfram