ABBY LINFORD isn't your ordinary 9-year-old. She's a quiet and a bit more mature than the other girls at Van Horne Elementary. This isn't Abby's fault however. When she was just a 3-year-old her father passed away which resulted in a little girl that had to grow up way too fast. Because of this, Abby is considered a bit of an outcast from the other kids at school.

Then one day she meets Issac, a new boy in the neighborhood. He himself is a bit of an outsider and this seems like a natural friendship. That is, until Abby's discovery that Issac is imaginary.

"I'm too old for an imaginary friend," Abby says to herself. But, Issac has no plans of going anywhere... well, not without Abby, anyway. You see, Issac has come here to bring Abby back home with him to a place that has been expecting her for a long time, a magical world home to all Imaginary Friends, and a place that is in danger of being destroyed... unless Abby does something about it.