Told 'ya. It was written by Rick Riordan. 
 Rick Riordan was famous for series Percy Jackson and the Olympians : kids with Greek mythology in the modern world, The Heroes of Olympus: also with Greek and Roman mythology and The Kane Chronicles: kids with Egyptian Gods. 
 But not 39 clues. The Maze of Bones is nothing about mythology, or magic, or monsters, or spells,... etc. It just a story about two ordinary kids: Amy and Dan Cahill. 
 Amy was fourteen. She loved history, museum, library, especially reading books and good with encyclopedia. But she stutters when she's nervous, and she hates crowd. 
 Dan was eleven and Amy's brother. He loved ninjas, and foreign snacks, and collecting cards, and grave. He has a photographic memory and good with mathematics, and solving puzzles. Although he seems annoying to his sister, and Amy usually called him "idiot" and "dweeb". But deeply inside, they love and care for each other. 
 Well, Amy and Dan have a normal live with their awful Aunt Beatrice. Their mom and dad had died in a fire, which was an accident according to the police. But somehow, Amy and Dan knew it was not an accident. The only person they love is Grace Cahill, their grandmother. But Grace has gone. Amy and Dan went to her funeral. They felt miserable. 
 In the funeral, all the members of the Cahill were invited. Before she died, Grace Cahill left a video, said that each person has two choice: they will receive $1000 dollars and go home or join a game - finding the 39 clues and become the most powerful person in the world. 
 Most people left home with their money. Dan wanted money, but Amy chose the clues. She said that Grace wants them to find it. So both of them chose the Clues. 
 They also knew the truth about the Cahill: the most powerful and awesome family in the world. There was a lot of famous people in each branches. 
 There were four branches: 
 Janus - art : Wolfgang Mozart,Rick Riordan(lol), Harry Houdini, Vincent Van Gogh,.... 
 Lucian - spy, leadership, cunning, poison: Theodore Roosevelt, Benjamin Franklin, Napoleon Bonaparte... 
 Tomas - brave and strong: Annie Oakley, Neil Armstrong, George Washington, King Louis, .... etc 
 Ekaterina ( Ekats): intelligent, inventing - Thomas Edison, Marie Curie, Abraham Lincoln, etc... 
 But Amy and Dan also had enemies. The other branches are fighting for the 39 clues. 
 They will begin the adventure around the world to find the 39 clues, find the truth about which branch are they belong too, about their parents death. 
 They will have to face the worst enemy of four branch: Beware the Madrigals 
 The book is really interesting, you will know more about history through the adventure. You can also be a member of Cahill and start to find the clues on the website: http://www.the39clues.com 
 Hope you enjoy the book :)