Moo Montana, Dakota Dude, and Cowlorado Kid have to deal with four masked marauders who happen to be ladies of the Sewing B. Ranch led by Barb Wire Babs (the criminal alias of Miss Barbara). As Cowlorado Kid goes undercover in Barbed Wire Babs' group, Wild Bill Barker is kidnapped as part of Barbed Wire Babs' plot to make counterfeit money.
Bat Blastagun and his gang have escaped from prison where they find a shard of the comet that created Moo Mesa outside of Cowtown. Enlisting the help of the mad scientist Dr. Wolfgang Wolfenstein, Bat Masterson uses the shard to shrink everything.
On Halloween, Skull Duggery returns upon emerging from the cave-in of his mine at Skull Mountain in order to get revenge on Moo, Dakota, and Cowlorado. This time, he has obtained an age accelerating spell with the help of his fellow ghosts where they start aging everything in Cowtown.
Cow Belle and her sons have an underground hideout called Sidewinder City which allows other outlaws to use it in exchange of a share of what they steal. When Cowlorado Kid is captured during the infiltration, Moo Montana and Dakota Dude must find Sidewinder City and rescue him while also dealing with the Masked Bull.