Ever since she used the Firebird, her parents' invention, to cross through to alternate dimensions, Marguerite has caught the attention of enemies who will do anything to force her into helping them dominate the multiverse-even hurt the people she loves. She resists until her boyfriend, Paul, is attacked, and his consciousness is scattered across multiple dimensions. The hunt for each splinter of Paul's soul sends Marguerite racing through a war-torn San Francisco, the criminal underworld of New York City, and a glittering Paris where another Marguerite hides a shocking secret. Each dimension brings Marguerite one step closer to rescuing Paul. But with every trial she faces, she begins to question the one constant she's found between the worlds: their love for each other.