This is a decent old-school, i.e. young-investigator-style, juvenile adventure. It's a sequel to Blaylock's 1984 novel "The Digging Leviathan," an off-the-wall thriller that put a sort-of steampunk spin on the New Age adage that "you create your own reality." "Zeuglodon" re-envisions the central secret of that tale in a way that's intriguing but, IMHO, not really weird enough for today's young readers. I also have to say that despite a lot of decent cliffhanger moments the plotting isn't very tight, and although endings don't have to resolve EVERYTHING in a story, a little too much is left unresolved, if not simply abandoned, here. However the tween girl narration is well done, and the tale includes one of my favorite Blaylockian plot devices (the one involving Mrs. Peckworthy.) Nevertheless I found it somewhat disappointing and suspect that the book isn't going to be a hit outside the author's usual readership.
Semi-orphan Kathleen Perkins is in the care of her eccentric uncle Hedgepeth, a member of the Guild of St. George, a secret society which despite having an at least semi-international membership seems to do little beyond keeping a team near the Lake Windermere estate of the bizarre Peach family and maintaining a dusty museum of odd relics in a remote part of northern California. When an attempt is made to steal an exhibit that the curators apparently never much examined, Perkins and her cousins toy with it, revealing - a secret, albeit one known to archvillain Hilario Frosticos and the macguffin's natural heir, the daughter of Giles "Gill" Peach, a central character of the previous novel. Curiousity, courage, and-if-I-may-say-so-a-certain-disregard-for-the-rules wins the day.
I'm a huge Blaylock fan and devour everything he writes - there just ISN'T anyone *I* know of writing in his vein of humane, open-hearted whimsy. His best books combine zaniness with slice-of-life observation, interludes of mystical description, obsessive cranks who can manage to open their minds to strike to the core of truth, and flawed yet adaptive heroes. This book... isn't one of his best. Like many of Blaylock's other stories it revolves around a secret of vast implications but decidedly parochial application, so without those interludes of mystical wonder the tale seems a little... precious, maybe?
I'm not quite putting my finger on it. Blaylock has a tendency to retreat into nostalgia. The book's title tells (or reminds) us a lot about the author, without having anything much to do with the plot; the story's focus on the children, their very nature threatened by the adult world of social services and compulsory education, is likewise a gesture that misses an opportunity. Blaylock can take whimsy, peg it to reality with shafts of insight, and illuminate it with the mystic power of language. You'll find that in "The Digging Leviathan," "The Last Coin," "The Paper Grail," and "The Stone Giant," but not, alas, here.