"Ten Thousand Skies Above You" is a science fiction novel written by Claudia Gray and is the second book in the "Firebird" series. The book follows the story of Marguerite Caine, who is a traveler of multiple dimensions using a device called the Firebird.

In this installment, Marguerite is on a mission to save her boyfriend, Paul, who has been taken by his own evil doppelganger into an alternate universe. In order to rescue him, Marguerite must use the Firebird to travel through ten different parallel universes, each with its own unique dangers and challenges.

As Marguerite travels through these different dimensions, she encounters versions of herself and her loved ones, some of whom are allies while others are enemies. She must navigate complicated relationships and shifting alliances to reach Paul and bring him back to their own dimension.

Throughout the book, Marguerite grapples with the ethical implications of traveling between universes and the consequences of her actions. The story is filled with adventure, romance, and high-stakes action as Marguerite fights to save the person she loves while also uncovering deeper mysteries about the nature of reality itself.