"It's been two months since the Kaplan family hunted down the Serpens relic, but when the evil Galina Krause suddenly and violently reappears, Wade, Darrell, Lily, and Becca have no choice but to face her again. Now they must race to find an artifact said to be crafted by Leonardo da Vinci himself--perhaps the strangest Guardian of all. Along the way, they uncover another layer to Galina's sinister endgame . . . and there might not be enough time...