The Ballad of the Daltons

The notorious outlaws Dalton brothers (Joe, William, Jack, and Averell) have been arrested and imprisoned again. The lawyer Augustus Betting informs them that their uncle Henry Dalton was executed by hanging. He has willed his entire estate to them, on the condition that they kill the judge and jury who sentenced him. To verify that the task has been completed, they must be accompanied by a witness. Henry has chosen their archenemy Lucky Luke as the witness, because he was the only honest man which Henry met during his long life. Should they fail, Henry's fortune will instead be given to charity. The Daltons escape from the jail and they offer a deal to Lucky Luke. He can either cooperate with them and eventually get a share of the inheritance, or refuse and be killed immediately. Luke seemingly agrees to supervise the killings and even offers to help commit them. He is actually helping the intended targets to fake their deaths, while preparing to put the Daltons on trial for a series of attempted murders.