Keeper of the Black Stones (Stone Ends)

Awkward in his own skin, shy around girls and worried about anything and everything, Jason Evans is just like a million other teenage boys in high school, with one very large exception: he has been given a gift that allows him to jump through time. A set of stones has fallen into his lap that gives him access to any place - and any time - that he chooses. But along with that gift comes the responsibility of stopping the man who is using those very stones to travel through time and change history for his own purposes. A man who is now holding Jason's grandfather hostage, and threatening the world's very existence. Jumping through time with his best friend and body guard, Jason must enter the world of Medieval England, learn its customs, navigate unimaginable danger, and help Henry VII win the Battle of Bosworth, in the name of finding his grandfather, rescuing a beautiful girl from the clutches of a corrupt church, and destroying the one man who pledges to turn history inside out.