Though the creatures are initially caged, the circus owners don't realize how powerful they are, nor that they will return to the Nether Realms in an hour unless they get three others to take their place.
They break out of the cage and stalk the circus owners. The Marvels arrive to stop them, but initially have trouble figuring out how to deal with the creatures' various abilities.
But the Wisdom of Solomon does apparently kick in from time to time. The Marvels soon figure out how to deal with the creatures. But not long after that, they return to their civilian identities at a bad moment--the Marvels are actually kind of dumb in that regard.