A tragedy in the Montana Territory exacts a painful promise from Call that takes him on a haunting mission back to Texas.

Off the trail, Jake falls in with bad company, while Gus shares a bittersweet reunion with an old flame.

A deadly pursuit on the plains pits Gus against a sadistic renegade named Blue Duck.

Larry McMurtry's Pulitzer Prize-winning novel inspired this four-part paean to the Old West, which spins a colorful yarn around the exploits of two former Texas Rangers as they lead a cattle drive to Montana.