Superboy is flying with Krypto in the sky and heading back to Smallville when they see a circus train heading for Smallville. Some of the train's cars breaks loose and Superboy and Krypto stop the cars and reattach them to the train.
Later, as the circus starts to assemble, Superboy hears from the circus owner that he's plagued by accidents over the past few weeks to the point some believe the circus may be jinxed and he may have to close it. Inside the train, a man named Slagg tells a clown to do a better job sabotaging and hands him a faulty cartridge loaded with explosives for the human cannonball act.
As the human cannonball practices his act, the cannon misfires and the man is sent hurtling out of the tent but Superboy manages to save him.
Slagg sees this but is confident the sabotage on the trapeze ropes will work. Moments later, the trapeze rope breaks and the acrobats tumble downwards but Superboy and Krypto save them from harm.
Slagg attempts to wreak havoc by startling a number of bears with a shotgun blast but Superboy and Krypto cage the bears before anyone is harmed and resecure the big tent's ropes. Slagg shoots at Krypto during the latter and Superboy apprehends Slagg and the clown and it is learned Slagg was a former part owner of the circus who was caught stealing.
Later, Superboy and Krypto perform at the circus for the audience.