10 Great Movies You'll Only Want To Watch Once

Threads is without question the bleakest, most upsetting, most frightening film ever made. Produced by the BBC in the midst of the Cold War, it follows two families in the English city of Sheffield as their lives (and the entire world) are torn apart by a nuclear war between Russia and the United States.

Many films have tackled the subject of nuclear holocaust, but Threads is both the most realistic and the most horrifying. Written by the talented Barry Hines, with contributions from Carl Sagan, it portrays the true horror of global nuclear conflict like nothing before or since.

The beginning of the film, where we see Ruth Beckett and Jimmy Kemp deal with an unplanned pregnancy in the face of a looming war, is depressing enough, but once "Attack Warning Red" sounds and the mushroom cloud rises over the city, what plays out is the most affecting and haunting movie of all time.

There are too many images that will be seared into your brain to list here. A woman wets herself in fear as the mushroom cloud grows. Glass milk bottles melt and a cat writhes in agony as thermal radiation washes over the city. A man beats furiously at his burning wife.

But the horror does not end after the explosion. Ruth must live in a world unmade, trading sexual favours for rats and eating the raw meat of a dead sheep. She later gives birth unaided in a barn, and dies, blind and cancerous, when her daughter is only ten.

Nuclear war remains a frightening possibility, and Threads is still a devastating look at exactly what that could mean. It's an important film, but one to approach with caution; it will change your life, and not for the better.

Which other disturbing films belong on this list? Share your picks below in the comments thread.