The Hidden Prince: Jasper's Sword Book one:

Bit a boy from Red Farm is a normal kid. He plays, has friends, and is an all-round nice guy. But one night there is a crash and a scream, he runs to his mother's room and finds that she's gone, the only thing left is a note. The note tells him and his friends that they must embark on an adventure full of cunning nobles and daring assassins. The story follows Bit and his friends through this adventure that will test their skills and their minds. And the whole way there is an underlying mystery. So when you reach the end Bit will discover who he truly is.