In 1904, nine-year-old Samantha, an orphan living with her wealthy grandmother, and her servant friend Nellie have a midnight adventure when they try to find out what has happened to the seamstress who suddenly left her job.
In June 1907, twelve-year-old Samantha looks forward to a happy summer with Nellie and her younger sisters at Grandmary's country home in the Adirondacks but a series of mysterious accidents on the property lead Samantha to suspect that someone is deliberately causing trouble.
When she discovers that Nellie and her sisters have been sent to an orphanage, Samantha, now living with her aunt and uncle in New York City, tries to help her friends as much as she can.