Egghead and Olga, Queen of the Cossacks, steal two pounds of Radium from the Gotham City Radium Center. Using it in their "Zapping Machine," they attempt to hatch an ancient Neosaurus egg, planning to feed the baby dinosaur a meal of Batman, Robin, and Batgirl. Surprisingly, the machine seems to be working. But when the egg cracks, the baby Neosaurus is more than they can handle.

Egghead and Olga, Queen of the Cossacks, kick off their return with several thefts from the Gotham City Museum. Egghead begins planning a series of heists - intended to provide him with the dowry needed to marry Olga. Swiping 500 pounds of dehydrated caviar goes off without a hitch. But when Batgirl attempts to outfox Egghead, she is instead captured by the villain. It's up to Batman and Robin to find the villains' hideout before Olga's Cossacks make mincemeat out of their crime fighting friend.