When Penny Rooney is assigned to write a poem about herself, she’s stumped. She thinks of herself as half of a whole with her best friend, Cricket—until she’s blindsided by the news that Cricket is moving away. Nothing is going right. But when Penny and her sister are swimming in the creek behind their house, Penny sees something impossible: a dolphin. Penny names the dolphin Rose, and she feels an immediate connection. Then, at the end of spring break, Penny’s cystic fibrosis begins to flare up. The only thing that reassures her is her bond with Rose, who is also sick—she was diagnosed with pneumonia by a local marine biologist and is given antibiotics not unlike those Penny inhales every day in her nebulizer. As much as Penny takes solace in her connection to Rose, Penny might also be the only person who can get Rose back to her pod.