When her family moves to Philadelphia's Society Hill neighborhood in 1866, Addy discovers that her new home holds dangerous secrets--including one connected to the North Carolina plantation she had escaped from only two years earlier. Includes a brief overview of the experiences of African Americans during Reconstruction, the period immediately following the Civil War.

"Twelve-year-old Rufus has nothing he can call his own. So when he's recruited by a shady showman to secretly operate a mechanical chess player called the Turk, Rufus sees an opportunity he can't turn down. But the job must be kept secret, and Rufus worries about what has happened to the previous operators of the Turk, who seem to disappear as soon as they are no longer needed. Can Rufus figure out the truth -- before his questions lead him into...

"In 1820s Philadelphia, a girl finds herself in the midst of a rash of gruesome murders in which her father and his alluring assistant might be implicated"--

When Dominique, Eric, Josephine, and Ajay return to the Smithsonian they see that modern animals are extinct and dinosaurs have been brought back to life, so they time travel to the 1876 Philadelphia Exhibition to stop this wicked plot.