When a mysterious letter written in code arrives at King's house for his human, Kayla, he follows the trail of the person who left it.

Marigold concocts a mystery that finally gets her and her friends into the boys' private eye club.

"A trip to a museum to learn about Ancient Egypt turns into a new case for the Code Busters when they discover that someone may be stealing artifacts and replacing them with cunning forgeries"--

An intruder at mad scientist's Petty Potts' house interrupts her latest experiment, trying REPTOSWITCH on twins Josh and Danny, and when they return home they find a package that sends them on a mysterious quest.

When Iranian-American Kamran Smith learns that his big brother, Darius, has been labelled a terrorist, he sets out to piece together the codes and clues that will save his brother's life and his country from a deadly terrorist attack.

An unbreakable cipher, a dead priest with expensive shoes, a hermit who converses with saints, an angry French girl, and much more might stop an ordinary fifteen-year-old safe-cracking genius, but not Percy St.-John. He's out to prove he did not steal a mysterious ancient book that may hold the key to mankind's greatest hope and greatest danger.

Second-grader Sam Graham wants a cell phone to do research and share information but when his parents say no, he devises a new plan that starts a fad at school.

"Why would Quentin Herms flee into the Quag? There was nothing in the Quag except certain death. Vega Jane has never left the village of Wormwood. But this isn't unusual--nobody has ever left the village of Wormwood. At least not until Quentin Herms vanishes into the unknown. Vega knows Quentin didn't just leave--he was chased. And he's left behind a very dangerous trail of clues that only she can decode. The Quag is a dark forest filled with terrifying...

A million dollars, or a clue? Police report a break-in at an elite hotel, and the suspects sound suspiciously like Amy and Dan. There's a car and speedboat chase and an angry mob! When there's a clue on the line, anything can happen.

Amy y Dan ya no pueden más: además de ser los primeros en encontrar las 39 pistas, deben intentar reconciliar a toda la familia Cahill. Pero hay un secreto que los Madrigal no les han contado y que podría costarles todo lo que han conseguido... Los Cahill son la familia más poderosa del mundo. El secreto de su poder se encuentra escondido por el mundo bajo la forma de 39 Pistas. After crossing five continents and solving some of history's most...