Survival Game (2) (The Apocalypse Duology)

Katya is a scientist, working on a top secret project for the Russian Empire. Due to her classified knowledge of alternative worlds, she's being blackmailed into working as a spy—and her father's life is at stake. She must hunt down a mysterious artifact that could give the dying Tzar his dearest wish—new life. But it's hidden on an alternate Earth, on an American-controlled island. She'll have to go deep undercover to gain access. However, if they use the artifact, the Russian Empire, the Americans' beleaguered territories, and all linked versions of earth face extinction. Katya discovers the truth with Jerry, an American survivalist based on the island. Together they must stop the artifact being activated, at any costs.