In the year 2597, Earth's colony world of Mariposa is shared with an alien race, the Tipruii. When war breaks out between the human colony and the aliens, Fiona learns that her future will be the price of peace. To save her people, she will be the tribute in a treaty marriage to the Tipruii princess, Simaala, and spend the rest of her days on the other side of the wall between their races.

As the war escalates, Simaala and Fiona navigate the confusion of new cultures and new desires to find a love that will transcend their differences. But not everyone wants peace, and Fiona is in more danger than she knows, putting all their plans and the fate of the human race in jeopardy.