The young Parisian siblings from McClintock's well-loved Adèle & Simon embark on a second highly successful adventure, this time on a train journey through the United States with their Aunt Cécile. Sepia-colored endpapers trace their cross-country route on an old railway map, creating an early-20th-century setting, and the artist's characteristic ink-and-watercolor work depicts each of 12 destinations in impeccable period detail. Once again Simon loses one of his belongings at each stop; the hide-and-seek game that supports this skimpy storyline is enticing, although so subtly presented that inexperienced readers may miss it. Astute readers will also enjoy the well-researched endnotes, which provide historical and geographical background for each place the trio visits and indicate the presence of historical figures, too, in many illustrations. This bonus element encourages even closer attention and may be the start of a child's own journey out of the book, toward further exploration of the people and places so magnificently rendered here. Ages 4–8. (Aug.)