Surviving summer vacation

Lewis and Alison's vacation should be lots of fun. Driving to Yellowston National Park in a motor home, seeing all the fantastic sights, getting to know their new neighbors... the trip should be a blast. It turns out to be anything but. First they discover that their hosts, the Rupes, have no interest in their own children. Even worse, two strange men seem to be following them. Could they have somthing to do with the one-hundred-dollar bills little Billy Rupe keeps finding in the motor home? Lewis in afraid the answer is yes -- and he should be.