The Daltons have forgotten who they are--even Averell isn't hungry anymore! 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.