The 39 Clues book series of ten books is a series of mysteries written by different authors Each book has one to ten clues in it to help reach something (the final prize) that will make the person who finds it the most powerful person on Earth. It's a race between families in the five branches of the Cahill family. The branches are: Lucician, descended from Luke, the clever and cunning Cahill, (2) Ekatrerina, descended from Katherine, the genius Cahill, (3) Janus, descended from Jane, the artistic Cahill, (4) and Tomas, descended from Tomas, a super strong Cahill. All the descendants have the same talents as their famous ancestor. These four Cahills are well-known, but few know of the fifth ancestor, Madeline whose descendants are called. Dan and Amy are Madrigals.
"Into the Gauntlet," written by Margaret Peterson Haddix is the wonderful last book to the clue hunt. The final prize that they've all been searching for and risking their lives for will fall into someone's hands. Amy and Dan, the main characters, are 14 and 11-year old siblings from Massachusetts who must do something that seems impossible with the five branches of the thousands of years old Cahill family.
My favorite author in the series is Rick Riordan, also the author of the Percy Jackson series who started this mystery series with The Maze of Bones. Other popular authors who have lent their talents are Gordon Korman and Jude Watson. If you like adventure then you should definitely read this book series. There's not a moment when Amy and Dan get to lay back and relax for more than an hour. It's a great story and I recommend it.