The innovative work with espers in Academy City has made remarkable strides in science and technology, thanks to their extraordinary abilities that defy the fundamental laws of physics. There is none more powerful than Accelerator, a Level 5 esper who suffers from severe brain damage but still outperforms his peers. Alongside him is Last Order, a guileless young girl whom he vows to protect at all costs, despite his cold exterior. Though Accelerator's injuries are healing, a sinister group infiltrates the city's Anti-Skill organization, plunging him into a new conflict. When a mysterious woman requests his aid in searching for Last Order, Accelerator realizes the danger he and his charge face. As the threat intensifies, he must resort to his former malicious ways to ensure the safety of those he holds dear.