The 39 Clues, Book 6: In Too Deep

The 39 Clues, Book 6: In Too Deep by Jude Watson

In the sixth 39 clues books, the heroes explore Australia and Indonesia. There are surf "attacks", gliding in escapes and many bits of action. The kids uncover more about their parents deaths, but have even more challenges trusting people.

The 39 Clues, Book 5: The Black Circle

The 39 Clues, Book 5: The Black Circle by Patrick Carman

The fifth 39 Clues book takes place in Russia. They need to travel to various cities to find the clues. Their super-rival also happens to be Russian, and will work at anything to stop them. This time they create some sort of alliances with other families and take the advice of a mysterious friend. There is plenty of action to keep things interesting.

Beyond the Grave (The 39 Clues, Book 4)

Beyond the Grave (The 39 Clues, Book 4) by Jude Watson

In book 4, the heroes journey to Egypt in attempts to find clues. They make and break allegiances as they seek to find the clues.

The 39 Clues, Book 3: The Sword Thief

​This 39 Clues book takes them to Japan. They almost don't make it. Their competition manage to incapacitate an airline employee and call them for "special screening" in order to take their boarding passes and jump on the plane. Luckily, their uncle helps them to fly privately. They do some investigation and then get ready to set out for the next clue. This book didn't seem to be centered around the nuances of a well-known historical figures as the previous two were.

The 39 Clues, Book 2: One False Note

The second 39 clues books takes a turn towards the arts. They discover that artists from Mozart to Rembrandt were all part of the family.  In this book, the clues are centered around Mozart. Our heroes travel to Austria and Venice as they attempt to uncover more information. There are even an additional set of catacombs. This book continues the adventures of the Cahills as they compete to find the clues. The two children have many near misses as they try to beat others to the clues. The book is short and sets things up for the next one in the series.

The 39 Clues, Book 1: The Maze of Bones

A brother and sister's parents have been dead. They have been living with various caretakers, but have been most close to one relative, Grace Cahill. After she dies, she promises her relatives either a million dollars or a chance to search for an answer through 39 clues. The children opt for the clues, even though it can lead to death. They enlist a babysitter to help them on the travels. Their "evil" relatives are also on the quest and manage to show up just as they discover something. There are many narrow escapes from death. They also discover that the are related to just about every important historical character. In this book, the focus is on Ben Franklin and a conclusion in the Paris catacombs. The book is nice and short and loaded with action.