This is a powerhouse of a picture book not unlike Chris Van Allsburg’s The Mysteries of Harris Burdick. There are inexplicable, eponymous Rules of Summer, dictated by an older brother to his younger sibling. The rules are simple, straightforward, and, as in familiar sibling territory, arbitrary. The art is magnificent. Thickly textured paint creates haunting, luminous landscapes that the younger brother must navigate until the older boy suddenly, impulsively, forgives all (all what?) and forgets his dictatorial edicts. In the final scenes, he lovingly rescues and befriends his brother. Here, the colors of joy in the double-page spread are palpable. Shaun Tan, author of The Arrival—my favorite wordless book and a Hugo Award winner—is superb again.