When a ghostly foe begins stealing from the highest buildings in Twinford, Ruby Redfort is ready to defy death one more time to capture the bandit.

Twins Josh and Danny continue following clues leading them to marbles filled with scientific code, despite the fact that mad scientist Petty Potts' REPTOSWITCH formula is having some very strange side-effects.

Kiki and her friends learn about coding as they compete to be the escort for young narwhal who will visit Trident Academy with her famous parents. Includes glossary, key to the codes used, and information about safeguarding narwhals' habitats.

Five years after seventeen-year-old Rose's mother and Joshua's father disappeared, when the step-siblings reconnect in London, Rose witnesses two murders which she fears are linked to coded notebooks Joshua has found and his investigation of the disappearance.

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,...

"When seven members of their family were kidnapped by a sinister organization known as the Vespers, thirteen-year-old Dan Cahill and his older sister Amy vowed they'd stop at nothing to bring the hostages home. But then the ransom comes in and the Vespers demand the impossible. Amy and Dan have just days to track down and steal an ancient map. The only catch? No one has seen the map for half a century. Now Amy and Dan are on a desperate search that...

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.

Twelve-year-olds Ambrose, Tom, and Frankie are transported to the boys' hometown of Freedom Falls, Ohio, in 1852 when Frankie blows her Romani family's magical trombone, and to return home they will have to use both Morse code and the ancient form of divination known as the I-Ching.

As Cruz and his friends continue to search for the third piece of the cipher, a mysterious message arrives suggesting that someone close to him is working for Nebula, leaving Cruz unsure of who he can trust.

Fourteen-year-old Amy Cahill and her younger brother Dan thought they could return to their regular lives when they found the 39 clues. But the Vespers, powerful enemies, will stop at nothing to get the clues. And with the Vespers rising, the world is in jeopardy.