Amy and Dan are separated while trying to retrieve a clue which is guarded by thousands of soldiers and worry they cannot succeed apart.

Using their code-breaking skills, four middle-schoolers solve the mystery of the eccentric man who draws stick figures on his second-floor bedroom window.

Orphans Amy and Dan Cahill, continuing their worldwide quest to track down the thirty-nine clues that will reveal the secret of the Cahill family's power, follow a link to one of the planet's strongest fighters, and have a run-in with the unreliable Alistair. Amy and Dan Cahill have been located once again, this time in the company of the notoriously unreliable Alistair. Spies report that Amy and Dan seem to be tracking the life of one of the most...

Summer, 1940. Nineteen-year-old Jakob Novis and his quirky younger sister Lizzie share a love of riddles and puzzles. And now they're living inside of one. The quarrelsome siblings find themselves amidst one of the greatest secrets of World War II--Britain's eccentric codebreaking factory at Bletchley Park. As Jakob joins Bletchley's top minds to crack the Nazi's Enigma cipher, fourteen-year-old Lizzie embarks on a mission to solve the mysterious...

Amy and Dan travel to a distant land to follow in the footsteps of their most formidable ancestor yet, a military leader who teaches them the art of ancient warfare.

" "You are to report to Station X at Bletchley Park, Buckinghamshire, in four days time ... That is all you need to know." This was the terse telegram hundreds of young women throughout the British Isles received in the spring of 1941, as World War II raged. As they arrived at Station X, a sprawling mansion in a state of disrepair surrounded by Spartan-looking huts with little chimneys coughing out thick smoke-these young people had no idea what kind...

Mac B. and his arch-nemesis are facing off at the Video Game World Championships! But first, Mac B. needs to crack an unbreakable secret code... can he solve it in time to defeat his enemy? Mac B.

During a class trip to Washington, D.C., the Code Busters have many opportunities to hone their sleuthing skills as they explore the International Spy Museum, the White House, and more, but when a classmate goes missing, a mysterious figure in a trench coat may be the key to solving the case.

After being taught in a boarding school run by whites that Navajo is a useless language, Ned Begay and other Navajo men are recruited by the Marines to become Code Talkers, sending messages during World War II in their native tongue.

When the Code Busters visit the Carmel Mission, a series of coded messages sets them on the hunt for long-hidden pirate treasure.