Rift (NECROTERRA, #1)

Series description:

In 2819 C.E., Lieutenant Jennifer Escalante is sent to Earth, the near-lifeless planet of her ancestors, to apprehend fugitive Doctor Max Gunnarsson after he steals the pinnacle of their world's technology—faster-than-light propulsion. However, they are forced to team up when they discover that a genocidal, alien species will arrive at their world, Azul, in less than four years. Escalante and Gunnarsson just need to learn to work together without killing each other first—...