When they see the tiny toy at the library, parents coax their kids into checking out bigger, sturdier stuffed animals instead, like Banjo the bear or Homer the owl. “It’s hard to be a brave explorer when you can’t go anywhere,” Marco Polo thinks. So when Seth talks his dad into checking out Marco Polo, the little mouse is thrilled. Seth’s excited, too, though nervous about his first sleepover at his friend Ben’s house. Seth sleeps with his well-loved toy bunny at home but fears being teased if he brings her. Instead, Seth brings the more easily concealed Marco Polo. When Ben’s older brother, Peter, mocks them at bedtime and Seth feels homesick, snuggling with Marco Polo helps him fall asleep. Soon Tulip the cat steals Marco Polo, bringing him to her garage hideout, where she’s collected purloined items, from socks and bottle caps to Peter’s old action figure and Ben’s stuffed monster. To rescue them all, Marco Polo proves as ingenious as he is brave. The series’ second title gently explores children’s fears and sensitivities. The message of empathy is reinforced by Graegin’s soothingly retro art. Seth’s family includes his dad and brother, all of whom appear to be White; Ben’s family presents Black.