Chase by Jessie Haas

Phin Chase was in the wrong place at the wrong time.

Now he's witness to a murder, and he must run fast and far to escape the Sleepers—the secretive, powerful organization responsible for the crime. With only his own wits to rely on, Phin hops a train to flee his small town. But there's a mysterious man on his trail—a man with a horse that tracks like a bloodhound. He could be working for the Sleepers . . . or he could be working against them. But Phin can't risk finding out.

Even if Phin manages to turn the tables on his pursuer, neither hunter nor quarry can imagine what will happen when they inevitably collide.