Sussy and Guy are best friends, fourth-graders who share their silliest thoughts and deepest hopes. One afternoon, the two of them decide they must have something of their very own to love. After a trip to the pet store, they bring home a spotted lizard, the one with the ancient face and starfish toes, and they name her Matylda (with a y so it's all her own). With Guy leading the way, they feed her and give her an origin story fit for a warrior lizard. A few weeks later, on a simple bike ride, there is a terrible accident. As hard as it is, Sussy is sure she can hold on to Guy if she can find a way to love Matylda enough. But in a startling turn of events, Sussy reconsiders what it means to grieve and heal and hope and go on, for her own sake and Matylda's.