Robert Simmons calls together the Mighty Orbots to save a spacecraft caught in a meteor swarm. The Orbots unite to save the ship and rescue two musicians named Dracos and Drax.
Dracos and Drax, however, secretly work for Umbra. They plan to summon with their music a magnetic monster at the concert that will reek havoc on Earth's defenses. With Earth weakened, Umbra can easily conquer the planet.
Dracos and Drax invite the Orbots to their concert. Bo and Boo decide to go. At the concert, they sneak backstage to meet the musicians. Using their music, Dracos and Drax hypnotize them and knock them unconscious. Dracos and Drax play at the concert and summon their magnetic monster. When they are finished, they stage blasts off and they head off into space with Dia in hot pursuit. Inside their spacecraft the musicians interrogate Bo and Boo until they are captured by Dia. Bo and Boo head off to meet with the other Orbots.
Meanwhile the other Orbots engage the Magnetic Monster. Unfortunately, the monster's magnetic properties prove a problem for the Orbots who are made of metal. Robert blasts the Monster to the rings of Saturn where the monster is frozen. The Orbots manage to escape the monster's grasp. They unite and defeat it.