Hawkman heads towards Silverland City where a silver mine had disappeared, where the Jovian spaceship shook loose some of the metal creatures, and they began feeding of the metal, turning a silver color in the process and starting to grow under the warmth of the Earth's sun. When Hawk arrives, he combats them unsuccessfully, but notes they are stealing the mine's payroll, then stumble into some dynamos, charging them with electricity. Securing 100 pennies, he drops on the creatures, shorting them out. Puzzled by the creatures robbing the payroll, he alerts the rest of the JSA of this fact.; The Atom must discover how the subway system of a great city has been destroyed. It seems that the Jovian beings are attacking the iron rails of the city's subway system, eating the tracks. When the Atom finds that he can't stop them, he talks to Hawkman, who explains what happened in Silverland City. Atom asks the Police to construct an oxygen accelerator for him, then confronts the beings, sprays them and the beings turn red. Atom explains that the beings were eating (and becoming) iron, and that by feeding that iron with oxygen at high pressure, he literally "rusted" the creatures to death!; As Frankie Tweed was at work, one of the strange Jovian metal men approaches him from the rear, grabbing him and the invention he was working on: an alloy as strong as steel, but as light as aluminum. G.L. saves him while also receiving a message from Hawkman thru the help of his power ring, giving him valuable information. Flying back to the factory, they discover the Jovians stealing cash from the safe. Knowing the beings are all magnesium now from feeding on that metal, and not wanting to destroy the factory, G.L. follows them into the countryside then destroys them with his ring.; The Jovians are feeding on telephone copper cables, and as they move on to find more of the metal, they stop off the at a bank to steal cash. When Dr. Mid-Nite can't stop them, he meets with metal workers to arrange a death trap for the beings, then leads them out of town, returns and throws a sack of cash into another bank. Inside, the creatures begin to feed on the hanging light fixtures, becoming ill and dropping over dead. Dr. Mid-Nite explains that when the beings ate the metal, not knowing that lead had been substituted for the copper, they simply died of lead poisoning.; One evening, strange, tiny metal men burst into a museum and began feeding on gold bracelets and rings. Then, a golden hand picked up a golden necklace, but before it could start feeding on it, the Flash appeared and begun struggling with the Jovians. Unsuccessful, Flash briefly saw Hawkman, and headed back to find the beings stealing pictures. An idea occurs to the Flash: gold is very malleable. Telling the Police to stay back, the Flash took on each of the creatures, reducing each to lumps of gold metal, thus saving the pictures and the solitary gold necklace.; Johnny heads to the frozen north to find the location of the spaceship, which landed there, and meets up with some friendly natives, who supply him with provisions and a dog sled for his trip. Warned not to seek the ship, Johnny won't listen and eventually finds it. Unimpressed, he kicks it and the ship eats the bottom of his shoe, but begins to roll down the hill, growing in size as it does. The natives think Johnny is responsible and try to do him in until brother John calls on the Thunderbolt to save him. Johnny then asks the T-Bolt to gather up the rest of the JSA and bring them there.; When Herbert Crawford, renowned scientist, doesn't appear at the meeting, Hawkman relates to the members Crawford's theory that Earth was soon to be invaded by metal creatures from Jupiter. Hawk had studied Crawford's calculations, even spotting a spaceship on one of the charts heading towards Earth. According to Crawford's studies, only metal was on board: living metal that could eat and grow! When reports come in involving strange occurrences involving metal, each member is assigned to investigate one of the areas involved with that occurrence.; The JSA ponders what to do with the ship. G.L. thinks acid may dissolve it, so he brings a string of acid vats to the scene, dumps them on the ship, which wastes away. They return to HQ to find Herbert Crawford waiting and he suddenly changes colors and begins to attack the members, stating that he has all the powers of the metal men. Hawkman figures, then, that Crawford also has their weaknesses, and that's how the members finally subdue him. He apologizes, and the JSA vow to help Crawford get re-established and use his knowledge for the benefit of the world after he is released from prison.