Having alloyed themselves together into one giant Metal Man, during a previous adventure, Doctor Will Magnus is now left with the task of separating his Metal Men. When Magnus, once more, rebuffs Platinum's amorous advances towards him, Platinum drags the alloyed Metal Man away in a huff. The Metal Men engage in various time consuming activities while they wait for Magnus to separate them. When Magnus' model girlfriend arrives, Platinum jealously trips the woman. Seeing Magnus leave for a night on the town, the dejected Metal Men decide to leap into the smelter, to save Magnus the trouble of separating them. Dancing with his girl, Magnus distractedly steps on her toes several times. Returning to his lab, Magnus encounters Tin, who informs him of the Metal Men's actions.
Magnus worries that certain alien alloys that were blended in with the Metal Men will react badly to the heat of the smelter. As if on cue, the Metal Men explode from the smelter, growing gigantic in size. Tin protects Magnus from the burning hot slag spilling over the smelter. Still fused together, the Metal Men break out of Magnus' laboratory. Magnus realizes that the alien alloys in their make-up are causing the Metal Men's responsometers to malfunction. Tin molds himself into a whirling helicopter blade, and carries Magnus out after the Metal Men. They find the Metal Men juggling rockets. The explosion of the colliding rockets renders Magnus unconscious. Tin molds himself into a parachute, to allow Magnus to safely reach the ground. As they fall, they are intercepted by Platinum.
No longer recognizing Tin, or Magnus, Platinum attaches Tin to her hair, like a pin. In response to the destruction of the rockets, the Air Force engage the Metal Men. A volley of missiles are fired, but Lead and Iron form a pillbox around the rest of their body, protecting Gold, Platinum, and Mercury from the attack. The force of the missile's explosion does dislodge Tin from Platinum's head. Molding himself into a hang glider, the humblest Metal Man escapes with Magnus. Seeing no choice but to destroy the Metal Men, Magnus decides to rebuild the Gas Gang. Once their reconstruction is complete, Magnus orders the Gas Gang to bring the Metal Men back to his lab, for melting. Unable to watch the destruction of his beloved Metal Men, Magnus asks Tin to record their final moments for him.
Oxygen magnetizes the alloyed Metal Men, but Lead is able to turn the magnetic attack back on Oxygen. Under the effects of the combined fumes of Chloroform and Carbon Monoxide, the Metal Men suddenly turn on one another. Carbon Dioxide freezes them solid, ending the battle. Helium inflates the downed Metal Man, allowing the Gas Gang to more easily carry them into the laboratory. Tin opts to share his comrades fate, despite being the only separate Metal Man. The Gas Gang turn on Magnus, hitting him with both chloroform and carbon dioxide gas. Tin breaks several electrical bulbs, then feeds the current through his body into the alloyed Metal Men. They, in turn, transfer that current to the Gas Gang, vaporizing them. In the haze of chloroform still filling the laboratory, Magnus sees the Metal Men looming over him. The combination of electricity and gas has, inexplicably, separated the team back into individuals.