When an experimental nuclear reactor malfunctions, two technicians—Herbert and Pinky Fuser—are caught in the blast and fused together into a single being of immense, unstable power known as Fusion. Traumatized and enraged, Fusion blames Spider-Man for their accident and threatens to destroy the city unless the hero faces him. As Fusion’s energy surges toward critical levels, Spider-Man struggles to stop the creature without killing the men inside. Using intellect and compassion, he separates the brothers just before a catastrophic explosion, saving their lives but leaving them physically and emotionally scarred.