It's Chad Sheppard's birthday and he's in for a big surprise! His best friend, Abner, a big furry Sheepdog can suddenly vanish into thin air. Not only is Abner invisible, but he can talk too... and he's a bit of a wise guy! But Chad already has enough problems fighting off two bullies who want to wreck his chances with Sophie, the cute girl next door. Now he has to hide an invisible, talking dog from his parents, and figure out how to get everything back to normal. That's not easy when Abner's invisibility wears off at the worst possible moments. A stolen top secret formula has accidentally fallen into his hands, and it's given Abner all the powers of a super spy. The government officials want their formula back, but so do the bad guys who stole it. Bumbling burglars Murdoch and Kane try to break into the house to kidnap the canine super hero. Nothing will stop the determined pair of clumsy crooks, not even their own stupidity. With the parents out of the house, Chad and Abner have to fight off the bad guys, get the girl, and save the day!