It’s been nearly 20 years since Bat Boy: The Musical had its world premiere on Halloween night in 1997 at the Actors’ Gang, the California theater company led by actor Tim Robbins. And it’s been a little more than 15 years since the show had a high-profile off-Broadway run in 2001, winning the Lucille Lortel Award for Outstanding Musical and the Outer Critics Circle Award for Outstanding Off-Broadway Musical.

Yet as his intellect and language skills develop, Edgar becomes more and more unhappily aware of his animal nature. It’s not just his pointy ears, darting tongue, and fangs; it’s the fact that he can’t eat the delicious home-cooked meals Meredith whips up for him. Turns out that the only nourishment Edgar can take is blood. Discovering this, Tom the animal doctor covertly satisfies that appetite, secretly feeding Edgar a steady supply of small furry animals. Tom professes to be Edgar’s friend, even a father figure—but he’s really only letting the lad live in order to please Meredith, his estranged wife, who has developed a strong maternal protectiveness toward the boy.

Through 7/24: Thu-Sat 7:30 PM, Sun 3 PM, Den Theatre, 1329-1333 N. Milwaukee, 773-609-2336, griffintheatre.com, $39.50; students, seniors, and veterans $34.50.