Legend of the Dragon Riders

Every one hundred years five guys all over the world are chosen between the ages of 17 and 21 to become dragon riders. They are chosen to rise above the dark five that try to wreak havoc and to destroy anything that is good in the world. The only thing that was differnt about this generation of riders was that the first time in 5000 years an 18 year old girl names Alex Leewood has been chosen by a dragon to stand by it's side and fight in the war. what makes her so special that this dragon would choose her? And will she be strong enough to defend the world of its evil?