Milo, whom we met in the previous book living on the magical train the Sesquipedalian ("Quip"), moves from minor supporting character to main character in this book. Though he's been living on the train for years, he's rarely stepped off it, except at the Archive. His scheming and secretive uncle Horatio has kept Milo unaware of much of his family history, and of the real world, where he was born.

This story opens with a copy of the “Wizard of Oz” sending Tilly's grandfather into a mysterious sleep from which he cannot awaken, after he touches the book's poisoned pages. Tilly and her family are desperate to find something to help him, and are even willing to listen to Horatio, when he and Milo arrive unceremoniously at the Pages & Co bookstore. Horatio's plan involves Tilly retrieving something from a book, but Tilly's grandmother refuses to entertain the plan.

When Horatio is also poisoned, Milo asks Tilly for help, and the two sneak away on the Quip, heading to the Archive, which is crumbling, then the world of the “Wizard of Oz” for what they'll need, then to Venice, Italy, where they meet the dastardly Alchemist, and his kind daughter Alessia. There is much running, peril, escapes, and a happy result for Tilly's family, but Milo knows that he still needs to find a way to rouse his uncle, which will entail dealing with yet another unknown figure, the Botanist.

Author Anna James continue to expand her world of BookWanderers and its magic. We learn a little more about the Quip, and there are interesting mysteries teased about Milo Bolt's family, and their relationship to all that is happening in the magic world.

This book was a little darker than previous installments what with the poisonings, and the various threats levelled at Tilly and Milo by the Alchemist. And the fact that it seems like his daughter is little more than a prisoner in her home. The previous villains in the earlier entries in this series were definitely bad people, but I think it's the Alchemist's chilling attitude that makes him feel so dangerous.

I am enjoying this series a lot, and am eager to get to book 5.

Thank you to Netgalley and to PENGUIN GROUP Penguin Young Readers Group for this ARC in exchange for my review.

I don't know how I missed this series until now, but I am glad to have discovered it. A world where individuals can "bookwander" into a story and a rare few can even read things out of books and into the real world. A magical train that travels through the layers of Story and the real world powered by book magic. A secret Archive with a mysterious caretaker. And, of course, brave children risking danger to save their loved ones.

Milo lives on the Sesquipedalian, or Quip, ”and he knew that, on paper at least, he made for a pretty good hero. He had so much in common with so many of the people he read adventures about: his parents had died tragically young, and the circumstances around the event were strange and secret; he was now looked after by an uncle who seemed to barely tolerate him, and he lived on a magical train that tracked down lost and forgotten books.” Despite the fact that Milo often feels more like a side character than a hero, he must do his best to save the day this time.

Together with Tilly and Oskar, whom he had met and worked with earlier in the series, Milo must find a way to save Tilly’s grandfather and his own uncle from a mysterious poison. They get a little backup from favorite story characters, travel through the pages of “The Wizard of Oz” to visit the Emerald City, and have dinner with the sinister Alchemist. Along the way they find a few clues about Milo’s family and the history of the Quip itself - and learn more about the power of story and friendship.

This is a wonderful book for readers who enjoy fantastic voyages like The Phantom Tollbooth, literary magic like Inkheart, or adventures like Mr. Lemoncello's Library that reference favorite characters and stories. You can read this one, even if you haven’t read the first three installments - but it will make more sense to read them all in order. Either way you will have a great time.