Trouble arises when Alex tries to save a friends daughter from a religious cult and is captured.

An undercover detective in Miami is captured by drug dealers when her cover is blown. Miami police ask Texas Ranges to help by going undercover as out-of-town dealers looking for drugs.

Joey Prado, the professional kickboxer whom Walker trained and helped when he was in trouble, has just graduated from the police academy. And he gets an assignment which has him going undercover to get a guy he knew who is now a drug dealer, who has plans to give drugs away. And the guilt of deceiving the guy gets to Joey.

A horse owner tries to bolster his horses' value by making sure they win all their races. But when another owner puts a crimp on his plans he kills the man and the trainer who was in his pocket. Walker investigates, and at the same time he tries to help his friend, who wants to put his horse Rainbow's End in the Texas Derby.

Carlos' nephew Jesse is accused of killing a cop during a drug raid since the murder weapon is found in Jesse's possession. The gun was left in Jesse's care by one of his friends, and Jesse is forced to take the blame to protect his mother.

The end is near ... in a show told mostly in flashbacks, a wounded Walker ascends through a manufacturing plant, wounded and using his gun one bullet at a time on killers as he recounts the story of a visiting African businessman who collapses from an Ebola-like virus after infecting several people. The businessman, who has since died of the virus, was a pawn in an African diamond-smuggling ring. Now Walker has the diamonds and a whole cartel is in the building going after him. A "Dallas"-like twist ending keeps Walker going (this show and the one after it were doubled up on the same Saturday night after being postponed due to extremely low ratings).