Marta and Dan's mom wants to help her transient sister, Pearl, who's accustomed to couch surfing, hostels, and park benches." ‘That's not how it should be,' said Mom. ‘Pearl will live with us.' " Pearl, whom the kids have never met, arrives with a loaded shopping cart. A man with a van brings more stuff. It fills the garage, the basement, and Pearl's bedroom—conflicting with Mom's penchant for tidiness. Dan reads the sentiments on Pearl's hat buttons: "Normal people scare me." Free-spirited Marta, age 6, accompanies Pearl on garbage-day scavenging, helping provide "a second chance" for castoff finds. Creative Pearl engages the diverse kids at Dan and Marta's day camp in decorating a salvaged coffee table with bottle caps—a gift for Mom. But Pearl's hoarding behavior and failed attempts to help domestically deepen the sisters' discomfort. As summer turns, Pearl grows increasingly despondent, and one morning, she's gone. Dan's tearful: "Why'd she go?…She left her stuff." But Marta "knew a mystery when she met one." Luxbacher's mixed-media illustrations supply visual clues: The buttons on Pearl's left-behind hat are obscured with fabric scraps—a double-edged gift for Rose? On the table rest three fabric napkins—polka-dot, just like Pearl's carry-bag. The ambiguity will have children and caregivers talking. Dan is dark-haired with light brown skin; the others present as white.A poignant look at a homeless woman and her family—a constellation too rarely seen. (Picture book. 4-7)