The The Crown of Fire (Copernicus Legacy #4)

This concluding book in bestselling author Tony Abbott's critically acclaimed middle grade adventure series is a mile-a-minute thrill ride. Perfect for fans of Rick Riordan and Ridley Pearson.

"Upon my life, I will." Across the centuries, every Guardian who has protected one of the twelve relics of the Copernicus legacy has taken this vow. But never have the consequences of the promise been more profound. The secret network of the great astronomer's spies is the target of an assassination plot, led by the despicable Galina Krause. And now the Kaplans are more alone than ever before as they race from France to Antarctica against a deadly ticking clock.

There is not much time left for Wade, Darrell, Lily, and Becca to find the remaining relics and defeat their enemies. But are they willing to risk the life of one of their own in order to save the world?