It is the forty fifth book in the series and was originally published in French by Dargaud in the year 1976 and in English by Cinebook in 2010 as Emperor Smith.

The situation escalates when Buck Ritchie, a notorious bandit of the region, gets to meet Smith, and convinces him to use his army to occupy the city.

Terrorized, the locals rank on the side of Smith, who sets out to reconquer all the United States, making Grass Town the new capital of the country.

Judged for high treason, Sheriff Linen and Whitman, the editor of the newspaper, cowardly plead their case, and are pardoned by Emperor Smith who gives a title and a ministry to each.

Convicted, Barney, the judge, is sentenced to death, commuted to life in prison, while Lucky Luke manages to escape, and plans to neutralize Smith, and free Grass Town.