What happens when a girl who keeps her heart underground meets a boy with his head in the stars? In this swoony and heart-rending romance, the award-winning author of A Heart in a Body in the World and Honey, Baby, Sweetheart beautifully captures the kind of love-and loss-that changes you forever. "Fans of Caletti's other works or the heady romances of Becky Albertalli and Adam Silvera will find exactly what they're looking for here." -The Bulletin for the Center for Children's BooksWhen Margaret sees Mars for the first time, it doesn't feel like love at first sight so much as future at first sight-she just knows right away that he will loom large in her life.When her job delivering pizzas brings Margaret right to Mars's doorstep, she can't deny their connection, even as the anxious voice in her head warns her about everything that could go wrong. Soon they're giving in to fate as their romance deepens over stargazing and moments under the endless night sky, where Mars shares his passionate interest in the Voyager's Golden Record-a time capsule of humanity preserved indefinitely in space. Together, they are absorbed by the unknowable questions we all face: How will we be remembered? What will we leave behind? And can anything truly be infinite?But even for someone who can't help but anticipate the worst, when the worst actually happens, Margaret is shattered. How can she move forward from tragedy when it feels like the world has stopped spinning? Somehow, she has to let go of the gravity of grief pulling her down and find her way back to the stars. But only if she can let the whole of the universe in-all the beauty and all the pain.