Time to even the score... That's what Deputy U.S. Marshal Custis Long has become--in fact they can chisel it on his tombstone because new deputy Henry Plummer is bound to get him killed. Longarm's boss has asked him to take the mayor's son under his wing and teach him the ropes, but young Plummer quickly proves to be greener than grass.   Longarm has a bigger problem, though. Henry Plummer has sworn vengeance on the two men who shot his mother in front of him when he was a child and would like nothing better than to use his shiny new badge to track the dirty dogs down. After Deputy Plummer is wounded stopping a botched bank robbery, a guilt-stricken Longarm vows to help him by finding his mother's murderers and giving them a taste of six-cylinder justice...