Two brothers, their dog, and their dragon conclude their adventures in this final installment of a trilogy.Orange-haired, pale-skinned brothers Paddy and Flynn live on a remote island that boasts both alluringly titled locales and fearsome fire-breathing dragons. Falling in step with their previous escapades (The Dragon Hunters and The Dragon Tamers, both 2017), the boys, their dog, Coco, and their dragon, Elton John, go for a wild ride up to Mount Astonishing, where the dragons annually congregate. However, the surprise presence of two human boys doesn't go over well, and Elton John must find a way to save the brothers and get them home before bedtime. As in the two earlier books, Russell maintains a narrative style of lilting quatrains in iambic pentameter, creating a lyrical read-aloud with a rhythmic flow. However, his worldbuilding—with its fantastic island containing such wondrous places as the Ridge of Rising Flame and Magic Terraces—never really breathes any life into the enticingly titled places and only briefly touches upon them in the boys' expeditions. The overall effect is resigned and docile; those seeking a dramatic dragon offering will be disappointed by the gentle cadence and muted adventures. Choi's illustrations range from small black-and-white sketches to large, soft-focus, full-color renderings that help reinforce this tale's quiet nature. Readers drawn by the augmented-reality feature will be disappointed to find it's just the same map as in the previous two books. A vanilla yarn best suited for bedtime. (Picture book. 3-7)