Jax and Ethan must decode an ancient Greek cipher to uncover the location of two magical urns before the urns are used to remove all faith and love from the world.

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.

It was 1798 when the Morningstarr twins arrived in New York with a vision for a magnificent city: towering skyscrapers, dazzling machines, and winding train lines, all running on technology no one had ever seen before. Fifty-seven years later, the enigmatic architects disappeared, leaving behind for the people of New York the Old York Cipher -- a puzzle laid into the shining city they constructed, at the end of which was promised a treasure beyond...

When twelve-year-old painter Esther gets stuck at math camp rather than art camp, she is determined to prove herself but someone leaves cryptic messages intended to drive her away.

In 1666, after four months away, friends Christopher Rowe, Tom, and Sally return to London triumphantly but, guided by coded riddles, face a conspiracy that threatens Christopher, as well as the King himself.

"Elusive art thief Lars Heinrich returns to New York City looking to settle a score. Super sleuth seventh-grader Edmund Xavier Lonrrot will need not only his photographic mind and artistic talents, but any skill he possesses with cracking codes as a string of the city's historical monuments become potential clues in what could become one of the greatest heists in history"--

657 days ago Meg's British father left their home in France to fight the Nazis, leaving some codes in a jar for her to decipher, and Meg and her French mother moved to the Perche, a region in France near Normandy known for its forests; now Meg watches the German soldiers in town, and sometimes carries messages for the French resistance--but suddenly things have gotten much more dangerous: there is a wounded British officer hiding in her grandmother's...

Sam Knox must use her archaeological skills and her knowledge of ciphers to crack the code of a mysterious diary and outsmart a nefarious brotherhood seeking to activate the curse of the Specter Queen. 1920s. Samantha Knox put away her childish fantasies of archaeological adventure the day her father didn't return home from the Great War. When a packages arrives at the antique bookshop where she works-- with a damaged diary inside-- Sam's peaceful...

"Summer is coming to a close on the East End of Long Island, and Alex is no longer welcome. A misstep at a dinner party, and the older man she's been staying with dismisses her with a ride to the train station and a ticket back to the city. With few resources and a waterlogged phone, but gifted with an ability to navigate the desires of others, Alex stays on Long Island and drifts like a ghost through the hedged lanes, gated driveways, and sun-blasted...

It was only a few days ago that Tess Biedermann, Theo Biedermann, and Jaime Cruz, along with a mysterious figure from the past, managed to survive an assault on the location of the latest clue in the Morningstarr cipher -- and, in the process, made a shocking discovery about their own connection to this one-hundred-sixty-year-old enigma. Now the friends are divided. Tess and Theo have no idea what the photo they found in Greenwood Cemetery means,...