John Liu, a sound technician for a New York City television news station, learns that his wife Nita Liu is pregnant, only for her to be murdered by knife-wielding thug Freddy Cufflinks. Grief-stricken and hungry for answers, Liu is assaulted by a street gang, but fights them off with a desperate, clenched resolve. He seeks out Detective Jimmy Williams, who tells him the authorities are doing all they can, yet Liu remains unsatisfied and restless, unable to let the murder slide into the background noise of a crowded city.
Driven by a need for personal justice, Liu decides to become a vigilante, slipping into a ninja outfit and arming himself with a sharp set of katanas and shuriken. He carries no hesitation as he interrupts an attempted gang rape, dispersing the assailants with precise, almost ceremonial throws of the shuriken. A new kind of fear starts moving through the streets as his actions go from isolated incidents to a running, living legend.
In the aftermath, Liu retrieves a purse and jewelry stolen from a tourist couple by pursuing the thieves on roller skates, an audacious sequence that is captured by onlookers from the ground and the newsroom. The footage lands on the front page, and among those watching is a cynical, deadly figure—the The Plutonium Killer—the ringleader of a prostitution ring that traffics women to an international clientele. The city’s attention widens from crime-fighting to something darker and more dangerous, and Liu’s face begins to appear in headlines as well.
As the vigilante’s legend grows, Liu stops another attempted assault on two women while his TV station co-workers—the fearless reporter Randi Rydell and the ever-present cameraman Jack—film the clash for a city hungry for spectacle. Liu’s crusade earns him admiration from some and fear from others, and he notices that the line between hero and target is thinner than he thought. He soon finds himself protecting a broader cast of people, including a young boy who owes him a debt of life-saving gratitude.
During a Halloween parade, the Plutonium Killer hypnotizes and abducts a woman, taking her to his car where he commits unspeakable acts while parts of his skin melt in the heat of a strange, nightmarish transformation. The next morning, the scene is grisly: the woman lies dead in an alley, and police quickly link the murder to the Plutonium Killer. The killer’s reach extends into the city’s power structure, and Liu realizes that his fight is about more than revenge—it’s about breaking a corrupt machine.
A pivotal moment comes when the Plutonium Killer and his associates attempt to kidnap Randi and Detective Janet Flores. Guided by an undercover Interpol agent known as the Pale Man, Williams shares crucial intel with Liu, confirming that the killer’s trafficking ring touches far-flung places and deep pockets. The investigation tightens, and Liu and Williams converge on the dungeon where the kidnapped women—including Flores—are held, liberating them and destabilizing the killer’s operation.
Disguised as Jack, the Plutonium Killer tries to lure Randi away, but Liu exposes the ruse by reflecting the sunlight off a mirror, melting the false face that had camouflaged the criminal. The chase crescendos in a hangar, where the Plutonium Killer abducts Randi once more and escapes in a helicopter. Liu follows, and a tense sword duel with the killer ensues, culminating in a daring bomb placement in the helicopter that blows it to ruin and ends the Plutonium Killer’s reign of terror.
In the aftermath, the NYPD briefly detains Liu, but the city’s chaos created by years of fear and corruption allows him to slip away as a new generation of hopeful vigilantes—children dressed in ninja outfits, chanting affection for the city—surges through the streets, restoring a strange balance between law, justice, and myth. The case against Liu remains open in some eyes, while in others he is celebrated as a protector who walked the line between law and legend, leaving the city to decide where the line should be drawn.
