Melody Bird is fascinated by the walled off "plague" house she discovered near the the graveyard, but she is even more fascinated by the mysterious boy, Hal, she finds living there in secret; he tells her he is a spy-in-training, a story that Melody's friends Matthew and Jake do not believe, and they set out to find out more--and uncover a riddle even more confusing than Hal's spy story.

"For a family with four kids, two dogs, assorted cats, and a constant stream of family and friends dropping by, life in the Austin family home has always been remarkably steady and contented. When a family friend suddenly dies in a plane crash, the Austins open their home to an orphaned girl, Maggy Hamilton. The Austin children -- Vicky, John, Suzy, and Rob -- do their best to be generous and welcoming to Maggy..

In alternating chapters, two teenagers describe how their feelings about themselves, each other, and their families have changed over the years.