When Amy and Dan learn the truth about the Madrigals and Grace Cahill's alternate will, these discoveries lead to the revelation of a secret about their family and a showdown with the man in black who has been following them.

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.

An escalating race to find the 39 Clues finds Amy and Dan pursuing a Clue guarded by thousands of the world's best-trained soldiers, an effort that separates them in explosively dangerous ways.

A single-volume omnibus of the three Cahill Files novellas, originally published as ebooks, explores the powerful Cahill family's roles in three high-profile historical events.

The third book in the CAHILLS VS. VESPERS series, the follow up to the worldwide bestseller THE 39 CLUES.

The Vespers have crossed a line. Amy and Dan were devastated when the Vespers kidnapped seven Cahills around the world, holding them hostage until Amy and Dan delivered an impossible ransom. But at least the hostages were Cahills - members of the world's most powerful family, trained to face all odds.Now the Vespers have gone too far. They've...

Amy and Dan Cahill's quest to find the million dollars takes them to Vienna, where they must outwit their power-hungry relatives as they seek to solve a clue involving Mozart.

The most dangerous secret in Amy and Dan's past is unveiled in Book 7 of the #1 New York Times bestselling series.

The hunt for 39 hidden Clues that lead to an unimaginable power have taken a heavy toll on fourteen-year-old Amy Cahill and her younger brother, Dan. They've just seen a woman die. They're wanted by the Indonesian police. They're trapped on an island with a man who knows too much about the death of their parents. And a tropical...

"Cruz Coronado grapples with an important secret as the gang heads to China in search of the second-to-last piece of the cipher. Under the watchful eye of a new adviser, life on the ship returns to almost normal...Almost. Just as things seem to be going smoothly, a familiar face shocks Cruz back into reality, and the final piece in this life-and-death scavenger hunt veers toward a dead end"-- Provided by publisher.

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.

Unexpected media attention in their Harlem neighborhood bring Shelby Holmes, nine, and John Watson, eleven, a new case that sends them undercover as figure skaters.