It's Viking-infested Paris, 885, in this second book by a second author in the Infinity Ring series (James Dashner's Mutiny in Time, 2012). As self-identified science and history geeks Sera and Dak ("we must be dealing with some sort of hidden variable aspect to the quantum entanglement" and "every modern-day European monarch is descended from Bill Helm the Vanquisher," respectively) travel through time with their linguist friend, Riq, to save the world from a still-mysterious evil organization. Many history-loving kids will be sucked in, while others will be hooked by the accompanying full-color poster-map (unseen) and corresponding 3-D online game.

This series (which has an online component) focuses on history nerd Dak, physics-obsessed Sera, and polyglot Riq as they travel through time to repair history. Mutiny focuses on Columbus's voyage; the writing is stilted and Native Americans are ignored. Divide, set in medieval Paris, appears to be more accurate, though the writing is formulaic. Fans of the 39 Clues books will be clamoring for this read-alike.

Vikings and time machines, together again. "History is broken," a character said, back in the first Infinity Ring title (A Mutiny in Time, 2012). He might have said that spelling is broken. The main characters in the series are named Riq, Sera and Dak, and they work with the Hystorians to fix the timeline. Like all good fantasy series, these books come with a vocabulary list. The time travelers have to look out for the Breaks, the Remnants and the SQ. Readers who skipped the first book may never make sense of the jargon, but they really need to know only one fact: The SQ is an evil organization. It wants to take over the world. In fact, it wants to have taken over the world millennia ago. Now, in Volume 2, the best way for our heroes to defeat the SQ is to join a Viking war. They jump into the fight without being certain they're on the right side. This is typical of the logic in the book, and readers may enjoy the story just because it makes them feel smarter than the main characters. The book is a perfectly competent adventure story. It's hard to go wrong with Vikings. But if you asked a classroom full of students to write about a Viking and a time machine, most of them would come up with something more inventive. (Science fiction. 8-12)