First there was Flight, of which I reviewed volumes three, five and seven. Then there was one volume of Flight Explorer, a version of Flight for younger readers that I also reviewed. And then came Explorer: The Mystery Boxes, a themed anthology edited by Kibuishi that looked awfully like Flight Explorer with less flight. Now, there's another volume of Explorer, which is more aggressively good for you than the first one (unfortunately).Flight was not officially aimed at younger readers, but it was a nice, soft-focus "all-ages" book, mostly by people working in and around the US animation industry and apparently having internalized that industry's obsessive focus on sweetness, light, prettiness, and eternal childhood. Those books, though, were also very big and expansive, so there was a variety of stories in that general gee-whiz neato-keano vein, and the art was always a delight. The Explorer books have all been shorter, and are now running to odd themes -- islands last time, doors this time -- and the kid-book scent of spinach is apparent more often than before.
Luckily, The Hidden Doors is less spinach-y than Lost Islands was; all of the stories here seem to agree that going through mysterious doors to explore new places is actually a good thing, unlike the last book. But every story here feels like it was adapted from the storyboards from a cartoon. I was going to say "a cartoon short," but that's not true -- they don't feel like the more elliptical, fun shorts that show up just before the big animated movies these days, but like initial sketches or pitches for those big movies themselves. The tone is not as emotionally deep as Pixar or as wisecracking as Dreamworks, but somewhere blandly in the middle, a pitch that could be molded either way depending on who picked up the option.
Now, they're all perfectly OK stories. And young readers will likely enjoy this. But I doubt more than a tiny handful will love any of these stories, or do for for any reason other than the art. It's all too safe and middle-of-the-road for that.