(3) YA Lady Mina Tretheway receives a mysterious telegram at boarding school written in code and is summoned to her family home. There, with the help of a family friend and a handsome American, Lady Mina is drawn into an exciting and dangerous mission that could help win the war. Despite a slow start, this is an engaging, action-filled World War I spy thriller.

Reviewer: Kristy Pasquariello

(2) YA In 1944 London, thirteen-year-old Bertie Bradshaw finds himself in the middle of espionage and intrigue, racing against the clock to unmask a Nazi double agent before WWII's top-secret D-Day operation commences. With red herrings, ciphers to decode, a subplot about a Jewish refugee, and cameos by real-life historical figures, there's never a dull moment. Back matter includes a "roster of terms, events, and historical figures" and solutions to the ciphers.

Reviewer: Martha V. Parravano | Horn Book Magazine Issue: January, 2019

(2) K-3 Illustrated by el primo Ramón. Morse's (1791–1872) failures are front and center in this spirited picture book, helping to humanize the famous inventor. While traveling in France, Morse first conceived of an electric telegraph machine and a code based on dots and dashes. Mishaps and delays frequently impeded success--a valuable lesson in grit and determination. Pencil drawings are digitally colored with earth-toned hues. Author's note and additional facts about Morse are appended. Timeline. Bib.

Reviewer: Tanya D. Auger | Horn Book Magazine Issue: September, 2019

(3) 4-6 Illustrated by Lily Williams. This very readable overview of cryptography throughout world history explains how different codes and ciphers work, moving from more basic examples (Caesar substitution, keyword cipher, pigpen cipher) to complicated encryption techniques (Nazi Enigma machines). Schwartz neatly weaves in math content and historical context, and she gives readers the chance to practice their deciphering skills. Final sections address cyber-security and hackers. Black-and-white illustrations and photographs are included. Bib., ind.

Reviewer: Tanya D. Auger

(3) 4-6 Illustrated by Sarah Watts. Emily Crane (Book Scavenger; The Unbreakable Code) is feeling the pressure of her outsized reputation as a puzzle-solver at publisher Garrison Griswold's elaborate mystery game night on Alcatraz Island. Then an actual mystery involving a reclusive author arises. Readers can work the puzzles alongside Emily and friends in this cheery celebration of San Francisco landmarks, ciphers and codes, and close friends working as a team.

Reviewer: Anita L. Burkam

(3) K-3 Illustrated by Liz Amini-Holmes. Young Chester Nez was sent to a missionary boarding school that taught English, but he ignored his teachers by retaining his native Navajo language and culture. As a soldier in World War II, Chester became one of the original Navajo code talkers, helping to defeat the Japanese. Muted illustrations enhance the informative biography. A portion of the Navajo code is appended. Timeline.

Reviewer: Luther B. Clegg

(3) 4-6 The series concludes in this sixth entry with code-cracking super-agent Ruby in search of a traitor within Spectrum's ranks. The familiar supporting cast is here to help, but another child spy may play an integral part in the mystery. Ruby is in top form, solving ingenious puzzles, performing impossible physical feats, and amassing clues to discover the solution. An exciting and satisfying finale for fans.

Reviewer: Grace Enriquez

(3) K-3 Ready-to-Read: Secrets of American History series. Illustrated by Valerio Fabbretti. This engaging easy reader pairs accessible, level-appropriate prose with full-color kid-friendly illustrations to introduce exciting, lesser-known facts about World War I. Choctaw Indian code talkers, razzle dazzle painting on ships for camouflage, and the story of pilot Eugene Bullard are covered. Back matter includes further explanations, craft ideas, a section on animal heroes, and a quiz.

Reviewer: Kristy Pasquariello

(3) 4-6 Alternator Books: Heroes of World War II series. This series provides readers with insights beyond the usual recounting of battles and politics commonly found in juvenile WWII resources, focusing instead on more personal aspects of the war and on anecdotes of heroism. Maps and archival images enrich the clear, informative texts; periodic "Hero Highlight" and "STEM Highlight" sidebars provide interesting context and detail. Reading list, timeline, websites. Glos., ind. Review covers these Alternator Books: Heroes of World War II titles: D-Day Invasion, World War II Resistance Fighters, Navajo Code Talkers, World War II Spies and Secret Agents, Attack on Pearl Harbor, and Japanese American Internment Camps.

Reviewer: Luther B. Clegg

(3) 4-6 In alternating narratives, Larson relates the World War II tales of Billie, an eleven-year-old girl, and a Marine named Denny, a Navajo Code Talker. The story focuses on Billie's longing for friendship and Denny's desire to preserve his Navajo heritage. Bear, an abused dog rescued by Denny and given to Billie, brings the two together. Historical fiction lovers will be drawn to the heartwarming story.

Reviewer: Luther B. Clegg

(4) YA Adapted by Laurie Calkhoven. This teen adaptation of Mundy's adult book reveals the largely untold story of thousands of talented young women recruited to work as code breakers during WWII. While it's difficult to follow the large cast of characters--and the highly technical explanations of the code-breaking process--the women's unique opportunity and subsequent achievements are fascinating, inspiring examples of unsung heroism. Reading list, timeline, websites. Bib., glos., ind.

Reviewer: Jessica Tackett MacDonald

(3) 4-6 Framed! series. Covert consultants for the FBI, twelve-year-old best friends Florian and Margaret (Framed!; Vanished!), return for a third caper. Here they must save their supervisor, Marcus, from taking the fall for a deep-cover Russian spy who has been using the Library of Congress to send secrets to the Russian embassy. This enthralling mystery about spies, libraries, and codes is cleverly spun with high stakes and amusing characters.

Reviewer: Lana Barnes

(4) 4-6 STEM Trailblazer Bios series. Each volume details the life of a significant person in a STEM-related field. Emphasis is placed on the individual's childhood, education, and development of a specific interest, as well as notable contributions. The prose is stilted but informative, and many photographs are included alongside sidebars of related information and "Tech Talk" quotes by the featured trailblazer. Reading list, timeline, websites. Glos., ind. Review covers these STEM Trailblazer Bios titles: Google Cybersecurity Expert Parisa Tabriz, Astronaut and Physicist Sally Ride, Code-Breaker and Mathematician Alan Turing, NASA Astronomer Nancy Grace Roman, Science Educator and Advocate Bill Nye, and Environmental Activist Wangari Maathai.

Reviewer: Danielle J. Ford

(3) 4-6 Illustrated by Sarah Watts. When their teacher, Mr. Quisling, begins a furtive book quest that results in fires around San Francisco, puzzle aficionados Emily and James (Book Scavenger) try to discover who's setting the fires, while simultaneously solving a Mark Twain–related "unbreakable code" to find treasure. Cryptographers and mystery lovers will enjoy following the clues as the smart plot and whom-to-trust character development keeps readers guessing.

Reviewer: Anita L. Burkam

(2) 1-3 Illustrated by Nancy Meyers. Narrator King, an exuberant dog, introduces himself and his human Kayla in the initial two entries of a new early-chapter-book series. Each story is a mystery: Treats concerns the theft of some dog biscuits, and Code concerns a substitution cipher. Repetition both within and between books helps boost confidence in beginning readers, as do the generous, plot-reinforcing illustrations. Review covers these titles: King & Kayla and the Case of the Missing Dog Treats and King & Kayla and the Case of the Secret Code.

Reviewer: Betty Carter | Horn Book Magazine Issue: May, 2017

(4) 4-6 The popular code-cracking teenage spy returns for another adventure, this one involving poisonous snakes, traitors, and vicious rumors. Ruby adds martial arts and the ability to see in four dimensions to her skill set, but otherwise the series formula is the same: expect suspense, witty dialogue, and intriguing puzzles, along with occasional uneven pacing and rambling moments.

Reviewer: Grace Enriquez

(4) YA Escape: Treasure Hunters series. Three teens follow a labyrinth of clues leading to sunken treasure aboard an ancient shipwreck. Cousins Chris and Carrie stumble on the first clue after the suspicious death of their archivist aunt and are joined in their quest by another archivist's daughter, Maddison. Some questionable plot twists are offset by likable characters and an intriguing mystery in this six-part hi-lo narrative. Review covers these Escape: Treasure Hunters titles: Deep Waters, Keyword Cypher, Secrets of the Old Church, The Treasure, Treasure in the Woods, and The Truth.

Reviewer: Renée Wheeler

(4) YA Escape: Treasure Hunters series. Three teens follow a labyrinth of clues leading to sunken treasure aboard an ancient shipwreck. Cousins Chris and Carrie stumble on the first clue after the suspicious death of their archivist aunt and are joined in their quest by another archivist's daughter, Maddison. Some questionable plot twists are offset by likable characters and an intriguing mystery in this six-part hi-lo narrative. Review covers these Escape: Treasure Hunters titles: Deep Waters, Keyword Cypher, Secrets of the Old Church, The Treasure, Treasure in the Woods, and The Truth.

Reviewer: Renée Wheeler

(4) YA Escape: Treasure Hunters series. Three teens follow a labyrinth of clues leading to sunken treasure aboard an ancient shipwreck. Cousins Chris and Carrie stumble on the first clue after the suspicious death of their archivist aunt and are joined in their quest by another archivist's daughter, Maddison. Some questionable plot twists are offset by likable characters and an intriguing mystery in this six-part hi-lo narrative. Review covers these Escape: Treasure Hunters titles: Deep Waters, Keyword Cypher, Secrets of the Old Church, The Treasure, Treasure in the Woods, and The Truth.

Reviewer: Renée Wheeler

(4) YA Escape: Treasure Hunters series. Three teens follow a labyrinth of clues leading to sunken treasure aboard an ancient shipwreck. Cousins Chris and Carrie stumble on the first clue after the suspicious death of their archivist aunt and are joined in their quest by another archivist's daughter, Maddison. Some questionable plot twists are offset by likable characters and an intriguing mystery in this six-part hi-lo narrative. Review covers these Escape: Treasure Hunters titles: Deep Waters, Keyword Cypher, Secrets of the Old Church, The Treasure, Treasure in the Woods, and The Truth.

Reviewer: Renée Wheeler