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.

Thirteen-year-old Ruby, a genius code-cracker and daring detective, gets an anonymous call setting a challenge that leads her to the headquarters of Spectrum, a highly secret anti-crime agency that needs her help to crack a code, but soon Ruby uncovers dastardly plans of the Fool's Gold Gang.

Four United States presidents have been assassinated - in 1865, 1881, 1901, and 1963 - each murder seemingly unrelated and separated by time. But what if those presidents were all killed for the same reason: a clause in the United States Constitution - contained within Article 1, Section 8 - that would shock Americans? This question is what faces former Justice Department operative Cotton Malone in his latest adventure. When a bold assassination attempt...

It's no longer a game. The body count is rising. Shaken by recent events, Amy and Dan flee to a distant land and trace the footsteps of their most formidable ancestor yet: a military leader of mythic proportions. Yet just as the siblings begin to master the art of ancient warfare, they confront a dangerous enemy that can't be felled with a sword: the truth. With the stakes higher than ever, Amy and Dan uncover something so devastating it changes everything...

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.

As the race to find the 39 Clues builds to its explosive finish, Amy and Dan must explore an ancient culture and steal a Clue guarded by thousands of the world's best-trained soldiers. It's the most dangerous Clue search yet ... and it may mean the end for Amy and Dan.

An adventure on the wide open ocean, and Ruby is all at sea. Can she crack the case while evading the clutches of the evil Count von Viscount? Well, you wouldn't want to bet against her.

Throughout the hunt for the 39 Clues, Amy and Dan Cahill have uncovered history's greatest mysteries and their family's deadliest secrets. But are they ready to face the truth about the Cahills and the key to their unmatched power? After a whirlwind race that's taken them across five continents, Amy and Dan face the most the difficult challenge yet -- a task no Cahill dared to imagine. When faced with a choice that could change the future of the world,...

"A cruise ship loses power in the North Atlantic. A satellite launches in the South Pacific. Professor Malcolm Clare--celebrated aviator, entrepreneur, and aerospace engineer--disappears from Stanford University and wakes up aboard an unknown jet, minutes before the aircraft plunges into the high seas. An extortionist code-named 'Viking' has seized control of a private warfare technology, pitting a U.S. defense corporation against terrorist conspirators...

Thirteen-year-old Dan Cahill and his older sister Amy race against time to find an ancient map that has not been seen for half a century and use it to redeem their family members who have been kidnapped by a sinister organization called the Vespers.