A family vacation is anything but restful when young Tom Pearson (Carter Jenkins), his siblings, and his cousins encounter an invading force of tiny aliens who are bent on conquering Earth. The aliens gain control of Ricky, the boyfriend of Tom's sister Bethany (Ashley Tisdale). Using an implant in his brain, they use him to carry out their plot. When Tom learns that the implant works only on grown-ups, he sees a chance to fight off the invaders -- but only if the adults are kept clueless.