Jeremy's troubles begin when his eccentric neighbor, Professor Twitchett, leaves him an 'experiment' for safe-keeping, a Jackalope! This so-called mythological creature looks like an adorable bunny rabbit, but comes with razor sharp antlers and is purported to be a ruthless killer. But when government agents show up at Jeremy's house, things look even more dire. It seems they want the Jackalope for their own purposes, and they will stop at nothing to get him. Jeremy must find a way to protect the Jackalope, and himself, so he reluctantly joins forces with Agatha, his holier-than-thou genius neighbor and classmate. With the Jackalope (and his weapons-grade-antlers) tucked away in a backpack, they have only one chance to save Jack and still find a way to get their science fair projects in on time.