A small comet with an unusually powerful magnetic charge is hurtling toward Earth. This is a job for Superman.

Meanwhile in some crooks' hideaway, Jay Vorrell, who is a brain-for-hire for no-good types, is masterminding a plot for some crooks. Clark Kent has suspected Vorrell of being the brains behind a series of robberies in Metropolis, but has been able to find the evidence he needs to prove it.

Superman makes short work of the comet, but discovers that the comets powerful magnetic field has permeated his body, and given him super-magnetic power. He quickly learns how to control the magnetic force, and utilizes it in apprehending the thieves, though they refuse to admit to Vorrell's involvement.

Back at the Daily Planet, Clark sits down to type his story, but inadvertently draws his typewriter to him magnetically. Seeing this, Lois Lane now knows she has the means to prove Clark is Superman, and starts tailing him, using a compass as a direction finder.

With his X-ray vision, Superman finds the hideout of Vorrell and the thieves. Figuring (correctly, of course) that Vorrell wears a steel bullet-proof vest, Superman has some fun with Vorrell, lifting him out of chair and making him "fly" out the window. The thieves, knowing that only Superman can fly, think Vorrell must actually be Superman, and accuse him of double-crossing them. The thieves attempt to make a getaway with their money, but Superman leads them to the police, using his super-magnetism to control the direction of their car.

As the police apprehend them, the thieves decide to spill all the beans about Vorrell. Superman goes back to the hideout and apprehends Vorrell.

When it is noticed that a huge electrical storm is headed toward Metropolis, Superman figures it is because his super-magnetism is drawing the storm to him. He flies off to a far distant mountain to draw the storm away. The storm follows and unleashes a fury of lightning on the Man of Steel. When the storm subsides, Superman discovers that the lightning has discharged all of his magnetism, and he is back to normal.

Back at the Daily Planet, Lois is still trying to expose Clark/Superman with her compass. When she finds the compass reacting to Clark, she thinks she has found her proof. However, the demagnetized Clark foils her by showing her a magnet he had in his pocket.

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