Boy and Tuck offer to build a clubhouse for Cat and Charlotte, but the two boys have a hard time letting go of their wonderful creation, driving the two girls up the wall! 

Mouse discovers that Dog is able to make a sad puppy dog that allows him to get whatever he wants. When Mouse asks Dog to use this trick to get the Professor to loan him a special rare rock for his experiment, Dog refuses. To get his own back, Mouse uses a special invention that allows him to impersonate Dog and get the rock. What happens next is absolute mayhem!