K-Gr 3—Beaty tells a poignant, heart-wrenching tale of love, loss, and hope. A boy narrates how every morning he and his father play the Knock Knock game. He feigns sleep while his father raps on the door until the boy jumps into his dad's arms for a hug and an "I love you." One day, there is no knock. Left with his mother, the child deeply misses his papa and writes to him for advice, receiving a moving letter in return. Collier's watercolor and collage illustrations enhance the nuanced sentiment of the text. Following the protagonist's journey from a grief-stricken child to an accomplished strong adult, the lifelike images intermingle urban and domestic backgrounds with the symbolic innerscape of the narrator. As the boy writes the letter and tosses paper airplanes out the window, he glides out on a life-size paper plane expressing his plea, "Papa, come home, 'cause there are things I don't know, and when I get older I thought you could teach me." Author's and illustrator's notes at the end of the book elaborate on the personal meaning of this eloquent story that speaks especially to children who are growing up in single-parent homes.—Yelena Alekseyeva-Popova, formerly at Chappaqua Library, NY