Callisto

She went to sleep in one world. and woke up in another. When Dr. Nicole Isbel is placed in cryosleep, she expects to wake up to the world she left behind. Instead, she opens her eyes to an Earth that is no longer hers. Humanity has vanished. The cities stand in eerie silence. And she is not alone. Extraterrestrial beings have taken up residence in the ruins, and one, in particular, is far too interested in her.
As Nicole searches for answers, she finds herself drawn into an unexpected alliance-one that challenges everything she thought she knew about science, survival, and connection. A sci-fi romance perfect for fans of steamy tension and alien encounters unlike any other.