In the American release, an introduction states that in 1983, a nuclear World War 3 had erupted between the Soviet Union and the United States of America which destroyed each other and the human race, leading to the creation of humanoid animals.
Mok, an aging yet legendary rock musician, is on the search for a very special voice that can unleash a powerful demon from another dimension, his dwindling popularity driving him to destroy the world in vengeance and immortalize himself in the process. After travelling around the world looking for the right voice, he returns to his hometown of Ohmtown, a remote, storm-ravaged village famous for its unique power plant. Meanwhile, at a nightclub, Omar, Angel, Dizzy and Stretch perform in a small rock band. As Angel performs her romantic ballad to a mostly empty audience, Mok hears her sing; he realizes that Angel has the voice he needs when a ring he is wearing reacts to her voice. Mok invites Angel and the band to his mansion outside of town, where the band is formally introduced to him and his assistants, the "Rollerskating Schlepper Brothers" Toad, Sleazy and Zip. Mok incapacitates Omar and Stretch with hypnotic "Edison Balls" as he takes Angel on a stroll through his garden and tries to convince her to join him. Although Angel is unaware of Mok's true intentions, she refuses to abandon her band. Unwilling to admit defeat, Mok kidnaps her and takes his blimp to Nuke York, where his summoning, disguised as a concert, will be performed.
Following their ejection from Mok's mansion, the band find out what happened to Angel and they follow the blimp in a stolen police car. Before they reach Nuke York, they are arrested by a border guard. Meanwhile, Angel attempts to escape with the unwitting help of Cinderella, the sister of the Schleppers. While sneaking through the ventilation system, Angel overhears Mok confirming his plans with his computer. At this time, the computer informs Mok that the only way to stop the demon is with "One voice, one heart, one song", but when Mok asks who can do this, the computer replies that there is "no one". Angel and Cindy escape the building and head to the zero-gravity dance club "Club 666", unaware that the Schleppers are following them. Dizzy's aunt bails out Omar and his friends, and tells them of the club. Angel and Cindy are intercepted and taken back to Mok's apartment, and the band tries to follow. Omar eventually bumps into Mok, who uses an impersonator to fool Omar into thinking that Angel has fallen for Mok. To manipulate Angel, Mok captures the band and tortures them with a giant Edison Ball to force her to agree with his demands. He also brainwashes them to ensure that they stay out of the way. The Nuke York concert turns out to be a disaster due to a power failure. Because the invocation requires a titanic amount of electricity, Mok relocates the summoning to Ohmtown, whose power plant has enough energy, though Zip expresses childlike doubts about whether their actions are good or evil. During the concert, a power surge causes overloads all over the city. The shock also brings Omar and his friends out of their hypnosis.
Stretch finds a poster advertising Mok and Angel's concert and Dizzy sticks with him to save her. After confessing that Omar saw Mok and Angel together, Stretch tries to remind him it's all mind games. Omar, still believing Mok's earlier deception, refuses to help Dizzy and Stretch stop the concert. They go without him in a stolen police car, but crash at the concert too late, as Mok forces Angel to summon the demon with her song. But Omar has a change of heart and arrives to free Angel from her electronic shackles before the demon can turn on her. When the demon attacks Omar, Zip seemingly sacrifices himself to save Omar's life. Angel tries singing to force the demon back, but her lone voice has no effect. But Omar joins in harmony with Angel, and thus the creature is weakened and driven back into its own dimension. Mok is thrown into the portal by the vengeful Toad, and as he is sealed away, he realizes that "no one" did not mean that the demon could be stopped; it meant instead that "no one voice" could, acting alone; two voices and two hearts singing as one were needed for the counter-spell. The audience believes the confrontation to have been part of the concert's theatrics, and the band continues their song in triumph.
