If there is a show which characterizes this kind of shows, than this is the one... A group of kids who investigate mysteries that happen near where they live. The group is composed by seven members (originally just four members) as well by one MIA member, one member in Australia, two members in England, and three members in 1928... A really strange but interesting group. But the main characters are Jamal Jenkins (he was the first one who Ghostwriter appeared to), Lenni Frazier, Alex and Gaby Fernandéz, Tina Nguyen and Rob Baker, and the story of the series revolves around them and the ways they find to stay one step ahead of everyone, all thanks to their good friend "Ghostwriter". The character of Ghostwriter is incredibly complex, and even though we never find out who he truly is, many clues are given to the main characters and to the audience as to who he really is. Some of the clues are these: He was a man when he was alive, but is now a ghost / He wanted to protect "the children" / He can only be seen by those to whom he reveals himself / He was alive before the F.B.I. was formed / He was alive before Walt Disney became famous. All these clues and many more lead us to suspect that the true identity of "Ghostwriter" is actually the ghost of Reverend Charles Dodgson, commonly known as Lewis Carroll, the author of the book Alice in Wonderland and its sequel. This mystery and others are just one of the many reasons why this series is so good.
In my own opinion, it's a crossover between Scooby-Doo and C.S.I., and a 10 is just the right number to charcterize this show.