Survival Game (Apocalypse Duology)

One civilization lies in ruins, but will they be next? Katya is a scientist, working on a top-secret project for the Russian Empire. She's also desperate. 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. But Katya's assignment seems impossible. 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 to this prize. And Borodin, the tzar's ruthless spymaster, has his own reasons for needing the object. However, ambition blinds these men to the facts. The artifact will call down terror from the depths of space. If they use it, 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 from being activated, at any cost. Two civilizations depend upon it.