When a virus makes everyone over the age of eighteen infertile, would-be parents pay teen girls to conceive and give birth to their children, making teens the most prized members of society. Girls sport fake baby bumps and the school cafeteria stocks folic-acid-infused food. Sixteen-year-old identical twins Melody and Harmony were separated at birth and have never met until the day Harmony shows up on Melody's doorstep. Up to now, the twins have followed...