The film
South America, 1960. A lonely and grumpy Holocaust survivor convinces himself that his new neighbor is none other than Adolf Hitler. Not being taken seriously, he starts an independent investigation to prove his claim, but when the evidence still appears to be inconclusive, Polsky is forced to engage in a relationship with the enemy in order to obtain irrefutable proof.
Synopsis from TMDB.
The name
Also in My Neighbor Adolf
Elsewhere on screen, Mossad