"On a spring morning, neighbors Valentina Kaplan and Oksana Savchenko wake up to an angry red sky. A reactor at the nuclear power plant where their fathers work--Chernobyl--has exploded. Before they know it, the two girls, who've always been enemies, find themselves on a train bound for Leningrad to stay with Valentina's estranged grandmother, Rita Grigorievna. In their new lives in Leningrad, they begin to learn what it means to trust another person....

When they are transported to St. Petersburg, Russia, twins Maisie and Felix meet Anastasia Romanov and experience a world filled with palaces and privilege.