And he knows that he craves revenge. Everything else is a dangerous maze that starts with the solution. Memory loss has long served as a shabby contrivance in comedies, mysteries and soap operas. He shows us a jigsaw puzzle one scattered piece at a time. They also might be manipulating the unhinged amnesiac.
Different details appear to be contradictory.
Some incidents are repeated several times, each from an altered perspective. Nolan's achievement is to keep us spellbound while dispensing data in erratic order. Amnesiac struggles to solve murder mystery.