As the impending disaster looms, a secretive cult known as Humarise initiates a nefarious scheme that could spell doom for the world. Their apocalyptic ideology hinges on the belief that Quirks, the unique powers held by certain individuals, are destined to bring about humanity's demise. In an attempt to avert this forecasted extinction, they have strategically planted Trigger gas bombs around the globe, designed specifically to brutally eliminate Quirk users by amplifying their abilities in a fatal manner.
In response to this grave threat, the World Heroes Association valiantly steps in, sending a battalion of Pro Heroes and students from U.A. High School's Hero Course to confront Humarise's predetermined targets and neutralize the remaining explosives. Among those dispatched to infiltrate what is believed to be Humarise's base in the nation of Otheon are Izuku Midoriya, Katsuki Bakugo, and Shoto Todoroki. However, upon their arrival, they find that their elusive foes have seemingly vanished, leaving them in a state of heightened readiness.
While they wait for further instructions, Izuku, Katsuki, and Shoto unexpectedly encounter a bold jewel heist in full swing. With the thieves eager to escape, Katsuki and Shoto pursue them, while Izuku chases after Rody Soul, a clever street kid who is motivated by his desire to care for his younger siblings.
Amidst the chaos, Alan Kay, a scientist working for Humarise, makes a hurried retreat with a vital briefcase, only to be ambushed by the ruthless Humarise agent, Beros. Their paths cross with Izuku's pursuit of Rody, leading to a dramatic crash that forces Alan to abandon his critical cargo. Just as this happens, Rody inadvertently snatches up the briefcase moments before Izuku can apprehend him.
As local authorities close in, Izuku cleverly employs his Blackwhip ability to escape custody alongside Rody. However, the chief of police in Otheon, sympathetic to Humarise's cause, publicly accuses Izuku of mass murder, prompting the young hero to go into hiding, as suggested by Shoto. Together, the pair heads to the neighboring country of Klayd, believing they can evade the watchful eyes of Otheon’s law enforcement.
In a twist of fate, Rody, overwhelmed by homesickness, decides to report the briefcase to the authorities. Unfortunately, the officers who arrive turn out to be Humarise agents in disguise, and they launch a surprise attack on him. Izuku, alerted by Rody's loyal bird companion, Pino, comes to Rody's aid. Together, they fend off Beros's savage assault, but not without Izuku sustaining injuries in the process. As Rody assists in bandaging his wounds, he opens up about his tumultuous past, revealing that his father’s abandonment to join Humarise left him and his siblings shunned by society. This emotional revelation puts them at risk when they reach the border of Klayd, only to be saved by the timely arrival of Katsuki and Shoto as Beros makes a harrowing escape.
Later, Izuku explores the briefcase further and uncovers a hidden compartment containing a childhood puzzle belonging to Rody. Curiosity leads Rody to solve it, only to find a USB device and data disk inside. The contents reveal a tragic message from Kay, explaining how he and Rody’s father, Eddie Soul, were forced by Humarise to create the devastating Trigger bombs. The device holds a kill code for these explosives. As the clock ticks down to the detonation of these bombs in just two hours, the newly united heroes scramble to locate and deactivate them while battling against Humarise soldiers. With the fate of the world at stake, Izuku and his friends quickly board a plane, piloted by Rody, as they head straight into the heart of the enemy's operations.
Meanwhile, Katsuki and Shoto are engaged in intense battles against high-ranking Humarise villains, and Izuku finds himself up against Flect Turn, who possesses the uncanny ability to reflect incoming attacks. Struggling against Flect Turn's formidable defenses, Izuku starts to feel defeated. Just as despair begins to set in, Rody arrives on the scene, creating an illusion of betrayal by coughing up the device in exchange for the safety of his siblings. Yet, prompted by Pino's cues, Izuku realizes this is a strategic ploy. Seizing the moment, Izuku channels One For All at full power and launches a concentrated blitz of attacks that overwhelms Flect Turn.
As the dust settles on this intense bout, Rody embarks on a daring mission to break into the command center for the Trigger bombs, fiercely motivated to succeed as time slips away. Even as he suffers serious injuries from the defensive laser system, he and Pino manage—just barely—to upload the device, halting the impending activation of the explosives and giving the world a glimmer of hope.
In the aftermath, the remnants of Humarise are apprehended, while the heroes recuperate in the hospital. As Izuku makes his way back to Japan, he shares a tender goodbye with Rody, filled with tears and a profound sense of longing.
Back at U.A., Class 1-A reunites, their spirits lifted by news of their victory. However, for Rody, this newfound tranquility is bittersweet, as he comes to realize his true aspirations lie elsewhere. Taking a job at the local bar, he begins to chase his long-held dream of becoming a pilot—an endeavor that promises its own share of exhilaration and challenges.
