In a future where time traveling is very real, the privilege is reserved for individuals born with a "Glitch" gene, who must also pass extensive training and testing at the exclusive Academy. When Regan, the Commander's daughter, and Elliot, an Academy urchin with no opportunity outside of his servitude, encounter a "Cocoon," a contraband time-travel letter sent from the future to warn them, they must overcome their feud in order to salvage everything--and everyone--they treasure. Martin expertly weaves the story through both Regan's and Elliot's perspectives, capturing their innermost emotions, especially their motivations and fears, as together they overcome frightening simulators and actual time travel. From the Boston Tea Party to Pearl Harbor, their history-based missions and inevitable friendship--or, at least, cooperation--will appeal to fans of action-packed dystopian stories like the Hunger Games trilogy or Ransom Riggs' Miss Peregrine's Peculiar Children series. This is the "grown-up" version of the beloved Magic Tree House chapter books, and it doesn't disappoint in honoring that legacy.

Time-traveling archenemies must work together to save their school. In a world where some people are born with a gene that allows them to slide in and out of time--to Glitch--children with that DNA are educated at a special school run by the government. Interfering with the past is against the law, and anyone who travels back in time to manipulate history is labeled a Butterfly and arrested. Glitchers are trained to stop Butterflies, and Regan Fitz, whose mom is commander in chief of the U.S. branch of Glitch Academy, has great intuition when it comes to spotting people intent on altering the timeline. She is, however, at the bottom of her class because school is a struggle. Her nemesis is Elliot Mason, who is at the top of the class, but he lacks the gut instincts needed to be an excellent Glitcher. Character development takes a back seat to premise and plot here. Regan and Elliot fight constantly and are in the middle of an epic blowup when a Cocoon--an object planted by a Butterfly to effect a change--in Regan's handwriting appears. The pair must work together to figure out its clues and succeed in their mission, all while avoiding detection and being arrested as Butterflies. The final time-travel sequences are many and dizzying, but the excellent pacing of the race to save the day overshadows this mechanics issue. Elliot appears black and Regan is white. A solid choice for readers who like history with their mystery. (Science fiction. 8-12) Copyright (c) Kirkus Reviews, used with permission.

In this buddy time travel tale by Martin (Hoax for Hire), Cadets Regan Fitz and Elliot Mason are rivals at Glitch Academy; they're training to use their rare genetic ability to travel through time and prevent "Butterflies" (so named for the butterfly effect) from altering U.S. history. Regan, 12, daughter of the Academy commander, is a mediocre student with solid intuition. Her classmate and social nemesis, Elliot, is at the top of their class but lacking in Regan's instincts. After they discover a letter sent from a future Regan to their current selves, they are forced to collaborate in a secret new program that trains Glitchers to work in pairs. A threat by Butterfly organization Mayhem against the Academy means that Regan and Elliot may have to do the forbidden: travel to the past to change the future. By using historical moments, such as the Triangle Shirtwaist Factory fire, for the missions, Martin imparts a bit of learning in an enjoyable fashion, while the protagonists' sparring morphs gradually and believably into a firm friendship. There is much here to please middle grade readers, whether they enjoy historical fiction, time travel, or tales of camaraderie. Ages 8--12. (June)

Gr 4--6--Regan and Elliot have been trained since birth to be Glitchers--time travelers who protect the past from Butterflies, the criminals who meddle in history. Regan and Elliot can't stand each other, but when they find a note from a future Regan that instructs them to travel back in time to prevent a disaster, they become not only teammates, but Butterflies themselves. It's refreshing to see a book that so effortlessly combines history and science fiction, maintaining the energy of a sci-fi adventure and the complexity of historical fiction. The fast-paced plot features plucky, well-developed characters, and first-person narration switches between Regan and Elliot, which works due to each character's strong voice. Martin's rules of time travel are simple enough for younger readers to follow, and the historical settings are comprehensive and thorough. Characters' discussions about the events they travel through provide context for readers. VERDICT With its dynamic plot, engaging characters, and sci-fi/historical fiction blend, this title will pull in a huge variety of readers, all of whom will be racing to see how the story ends.--Kristin Brynsvold, Tuckahoe Elem. Sch., Arlington, VA