Streets Of Laredo (Lonesome Dove #2) by Larry McMurtry; 1993. Softcover.

The final book of Larry McMurtry's Lonesome Dove tetralogy (chronologically) is an exhilarating tale of legend and heroism. Captain Woodrow Call, August McCrae's old partner, is now a bounty hunter hired to track down a brutal young Mexican bandit. Riding with Call are an Eastern city slicker, a witless deputy, and one of the last members of the Hat Creek outfit, Pea Eye Parker, now married to Lorena -- once Gus McCrae's sweetheart. This long chase leads them across the last wild streches of the West into a hellhole known as Crow Town and, finally, into the vast, relentless plains of the Texas frontier.

Published second of the four books but last in the chronology of the characters.