Rattler

the long version

Randall Foster was a young school teacher who got dragged into a deadly clash of clans. When the dust settled, the teacher was hand-picked by a covert government agency called The Service. Proving himself in a secret training program, Randall Foster soon has a new career, a code name 'Rattler', and a stubborn horse who does everything except obey. In a mild-mannered disguise, Rattler comes to Clearview, Kansas, in search of a depraved killer using the name Featherston - and walks straight into the ruthless killer's crosshairs.