Jack's five-year-old sister, Annie, is a genius. She enjoys the works of Shakespeare and has taught herself Spanish. She also has a vivid imagination. That's why Jack isn't too surprised when Annie starts telling him about an invisible friend named Sarah, who has arrived from the 25th century. But when Sarah turns out to be real, Jack has some very strange trouble on his hands.
- Publication Date: July 1, 2001
- Hardcover: 160 pages
- Publisher: Hyperion
- ISBN-10: 0786806168
- ISBN-13: 9780786806164