The 2015 movie Remember. Here’s the description from IMDb
With the aid of a fellow Auschwitz survivor and a hand-written letter, an elderly man with dementia goes in search of the person he believes to be responsible for the death of his family in the death camp to kill him himself.
I recommend against reading anything else about it if you think you might watch it
The 2015 movie Remember. Here’s the description from IMDb
I recommend against reading anything else about it if you think you might watch it