Lucky Luke catches traveling performer Otto abusing his hypnotizer skill for theft. He's jailed with the Daltons, who convince him to escape together, form a robbery gang and take revenge on Lucky. Otto hypnotizes a whole town, but Lucky remembers some cancel and other commands. Otto resorts to hypnotizing his own side, with weird side-effects, and Averill learned the skill.
The Daltons escape from Denver prison, over the Coloroda border, to Utah, the only state where they are still not wanted. So Lucky Luke has to wait before arresting them till they foul up, which is bound to happen as they met a slick con-artist who is bound to rival with them for the same victims.
Lucky investigates when a town gets divided over whether to believe that cattle theft is the doing pf green Martians arrived by flying saucer, or cleverly covering-up thieves as Luke assumes. Even an Indian medicine man seizes his chance to sell 'alien repellent' talismans.
Lightning renders dumbo Averill smart enough to lead a Daltons escape and evil, seizing command from Joe and aiming to rob Fort Knox. While Lucky Luke sets chase, the lightning wears off, so Joe goes looking for more electricity to reproduce the effect, but can only recur to a rain-dancing Indian medicine-man.
US Cavalry Colonel Oswald has orders to test fat Bertha, the White House's top-secret artillery pet project. Alas he looses control over it after the Daltons saw it, so they escape to get hold of it, but so want Indian chief Oochi Coochie and the now dismounted troopers. Lucky must arrest the Daltons again at risk of being bombed to Kingdom come, and the Colonel gets a surprise visit.
Exasperated by Queen Victoria’s unbearable superiority complex, President Grant decides to challenge “her majesty” to a contest: Lucky Luke VS Sherlock Holmes.
The cowboy who draws a gun faster than his shadow is back! Lucky Luke, the famous wandering cowboy fights crime and injustice, most often in the form of the bumbling Dalton brothers. He rides Jolly Jumper, "the smartest horse in the world" and is often accompanied by Rantanplan, "the stupidest dog in the universe".