Wyatt Earp, Billy the Kid, Doc Holliday, Tombstone, the O.K. Corral--the icons are so firmly embedded in American history that we might know nothing more about them than their names. But in this spare, moody riff on the events leading to the 1881 shootout at the O.K. Corral--the signature battle defining the violence of the Old West--Robert B. Parker shades the black-and-white starkness with sh...