Unleashed (Swindle #7)

Luthor, a former attack dog, is supposed to be on his best behavior now that he's in the care of Savannah, a girl who's easily a dog's best friend. But every time a certain truck passes by Savannah's house, Luthor goes into attack mode -- and chaos follows. Meanwhile, Griffin Bing is locked in the fight of his life with his archenemy, Darren Vader. Both are trying to win an invention contest -- and will stop at nothing to be victorious.