Gloomy Sunday takes its title from the song of the same name, made popular during the '30s and '40s (in the U.S., it came to prominence as a hit for Billie Holiday). Its brooding melody and dark, lovelorn lyrics were rumored to have had a fatal impact on many despondent lovers. Because of this it become known as the 'Hungarian Suicide Song.' It appears the moniker was largely exaggerated, but because of this it retained a dark history, culminating with the suicide of the actual composer in 1968.

The story for Gloomy Sunday marries the legend of the song with a background setting of World War II. At the beginning of the film we meet Laszlo, who is a successful Jewish restaurateur. Laszlo runs his establishment with his hostess and girlfriend, the beautiful Ilona. Ilona's beauty draws in and seduces many of the regulars at the restaurant, including their new pianist, Andras. As Ilona becomes involved with both men, they eventually learn to come to terms with their strained but mutually beneficial love triangle.

As things have a way of doing, they quickly become more complicated. One night Laszlo saves the life of a young German visitor who, after becoming so distraught from a mild rejection from Ilona, tries to take his life by jumping off a bridge. Laszlo pulls him from the river and nurses him back to health. Later in the story, the man returns to the city, only this time as a high-ranking officer of the Third Reich who has been assigned there as part of the occupation of Hungary.

At the same time, Andras gains notoriety for one of his compositions played at the restaurant. Originally penned as an ode to Ilona, the instrumental piece soon gains nationwide attention after being discovered by record company executives visiting the restaurant. However, after reports begin pouring in of its connection with a recent wave of suicides in the country, it begins to attract the wrong kind of attention for both him and the restaurant.

Laszlo's friendship with the German becomes more and more strained as the Jewish persecution heightens. When the German begins anew his advances to Ilona, only this time as someone of considerable and unsettling political power, it threatens to wreak more devastating consequences on both Laszlo and Andras.

There are two equally powerful and complex facets to the story that play out during the course of the film: war and music. War is perhaps easier to understand, but less settling to witness. As a story that largely takes place during the Holocaust, there are elements of it which are not easy to watch. It's not simply the Jewish persecution, which was horrible enough, but just as disturbing is the visual of watching a culture become deadened by a regime and philosophy until it becomes too weak to resist.

There are several instances where you see people just trying to go about their day, all the while people are being rounded up in the background. You never see anyone conspiring to escape or flee this situation as it spirals down into madness until the trucks pull up and take them out by force. This is a problem because the story needs as many people to simply go about their lives as possible. If everyone is actually worried about the pending oppression, then no one will have time to stop and listen to the music.