In 2012, when Sarah Ruhl was teaching creative writing at Yale, she became particularly close to the student Max Ritvo, a poet. When Ritvo began in the MFA program, he was in remission from pediatric cancer. But within a short time the cancer returned. Over the course of his illness, as his health declined, Ritvo exchanged letters with Ruhl. In 2018, two years after Ritvo died, Ruhl compiled their correspondence into a book. Now she’s adapted the book into a play. The premiere production is onstage at the Signature Theatre. —Jensen Davis