Deputy U.S. Marshal Custis Long is dispatched to the Pass of the North - the American - Mexican border city of northern El Paso and southern Del Norte - to extradite a prisoner from Mexico. The Federales, however, are being none too cooperative, leaving Longarm to bide his time on the American side of the city until his charge is released. Unfortunately, he learns he's made some enemies when some polecats use him for target practice. To find out who wants him dead and why, Longarm's got to ask questions on both sides of the border - and both sides of the law . . .