The 169-story treehouse

"Andy and Terry live in a 169-story treehouse...It now has a kangaroo-riding range, a Whatever-Weather-You-Want dome, and a hall of fun-house mirrors--the perfect place to hide from the truancy officer who is trying to catch them and Jill and make them go to school! Unfortunately, the hall of fun-house mirrors is also the place where their evil troublemaking twins, Anti-Andy, Terrible-Terry, and Junkyard-Jill, live in a doppelganger mirror, and they take advantage of the confusing to escape and wreak havoc in the treehouse. Can Andy, Terry, and Jill escape school, save the treehouse from the doppelganger mirror gang, AND get their book written on time?"--