Seventeen-year-old Retta Heikkinen is in love with a boy—a thoroughly gorgeous, captivating, and mysterious boy known as Hemingway. The situation is rather ideal: he likes her, she likes him. There's just one little problem. He's a blue heart, an android. Being in a relationship is its own complicated mess, but how long can a forbidden love last? Soon Retta discovers a secret that could destroy the uneasy truce between the blue hearts and humans, which makes life under the domes on Mars possible. Would exposing what she knows make things better or worse? And how can she know for certain without exposing the secret?