A man with no short-term memory tries to find his wife's killer. In truth, he was the one who killed her. His wife tricked him into giving her too much insulin because she was tired of dealing with him. Due to the traumatic nature of his wife's passing and his own mental defect, he was able to partially block this memory, attributing it to another person. There. I just saved you two hours of utter confusion. You're welcome. Film gets 5/10 for being backwards. Stop trying to be all fancy.