The Border Legion.

Wanted by the law in New York, Dr. Steve Kells heads west and arrives in an area controlled by an outlaw gang known as the Border Legion. When the gang's boss is wounded, they kidnap Kells and force him to remove the bullet. Not allowed to leave and being a wanted man, he joins the gang. Now wanted as a gang member also, he nevertheless plans a raid that will lead the entire gang into a trap.