Mac falls on a girl named Goo when trying to get a bobsled out of a tree, and she begins visiting Mac every day at Foster’s. With her hyperactive imagination, she creates a new friend one after another, which causes a big problem for the other imaginary friends in the house. After she creates so many imaginary friends that it crowds the whole house, the others have to sleep in the Foster’s bus and feel that Mac is responsible for Goo’s continuous visits.
