Terry's Family Studies teacher gives the class an assignment: to learn about the responsibilities of parenthood, they have to take care of an egg. The familiar exercise is given a high-tech twist -- each "eggbaby" has sensors which register the amount of care it receives and a computerized feedback system causes it to coo, cry, and giggle like a real baby. When Terry's assignment partner, vain cheerleader Blade Summers, unceremoniously dumps the eggbaby on him, he's forced to carry it with him when he's out as Batman -- even while chasing the notorious Ma Mayhem and her gang as they commit a series of daring ruby thefts.