Lucky Luke (english version) - Tome 49 - The Dalton's amnesia

After a fellow inmate, having received a blow to the head, forgets his own name and is freed as a brand new man, the Daltons start pretending to be amnesiac in order to escape the prison. So as to test their supposed amnesia – and hopefully allow them to retrieve their memories should it be real – they are put in familiar situations: bank hold-ups, train robberies ... under Lucky Luke's supervision, of course.