There was no backstory blurb this issue.
Kids, don't you hate it when relatives drop by without calling first? Well, the Young Heroes are no different, when Monstergirls uncle stops by for a visit things get exciting REAL quick! He's here to test her survival skills, and he's not grading on a curve! There's big monster action as he makes with the gnashing, and the hurting and the biting, and the hurting. Can the Young Heroes stop him before he "tests" Rita into a pool of redish goo? You bet they can!