Still looking for clues about their family, Amy and Dan hook up with the notorious Alistair Oh.

"Amy and Dan hit the high seas as they follow the trail of some infamous ancestors to track down a long lost treasure. However, the real prize isn't hidden in a chest. It's the discovery of the Madrigals' most dangerous secret and, even more shockingly, the true identity of the mysterious man in black"--Amazon.com.

"Are some secrets better left buried? As Amy and Dan track the next clue to a remote corner of the world, they make shocking discoveries about the source of the Cahills' power and the mystery of their parents' deaths. And as the threat of the mysterious Madrigals grows real, one of the clue-hunters makes the ultimate sacrifice. Amy and Dan have to decide how much they're willing to risk, and what they are fighting for. Can they avenge their parents...

"Amid assignments that take the Explorer Academy recruits from the iceberg-filled waters of Antarctica to the bone-dry deserts of Argentina, Cruz Coronado is scrambling to complete the last piece of the cipher. With Nebula agents and the elusive explorer spy still out there, his opportunity to recover his mother's world-changing formula is slipping away. But as Cruz has learned from his time aboard Orion, true explorers must never give up. Even after...

"Fourteen-year-old Amy Cahill and her younger brother, Dan, have had enough. Not only do they have to find the 39 clues first, they're expected to reunite their backstabbing family--the same people who killed their parents. But Amy and Dan haven't survived explosions and assassination attempts for nothing. They have a plan to finish the Clue hunt on their own terms. Too bad there's a final, fatal secret the Madrigals haven't told them. A Secret that...

There's something lurking beneath the surface of Stately Academy-- literally. In a secret underground classroom Hopper, Eni, and Josh discover that the campus was once home to the Bee School, an institute where teachers, students, and robots worked together to unravel the mysteries of coding. Hopper and her friends are eager to follow in this tradition and become top-rate coders. But why are Principal Dean and the rugby team suddenly so interested...

"It was only a few weeks ago that the Biedermann twins, Tess and Theo, along with their friend Jaime Cruz, followed the secrets of the Morningstarrs' cipher further than anyone had in its century-and-a-half history -- and destroyed their beloved home in the process. But the Old York Cipher still isn't solved. The demolition of 354 W. 73rd Street only revealed the next clue in the greatest mystery of the modern world, and if Tess, Theo, and Jaime want...