When a professor's experiments with his "magnetic telescope" endangers the city by pulling in a flaming comet from space, the mayor orders a stop to the experiments. Believing in the importance of his research and confident he can exert greater control of his device, he ignores the order and proceeds with plans to pull a larger comet in for a closer look. When the city police disable the telescope, the incoming comet descends out of control, forcing Superman to intervene to save the city from certain destruction.