Whenever you watch a truly terrifying horror film, there’s a mantra many of us silently repeat in order to bring ourselves down from any potential dread-induced anxiety attacks: ‘It’s only a movie.’ What happens, though, when the movie is based on a true story? In those cases, we may try to convince ourselves that the filmmakers are playing fast and loose with the facts for cinematic effect, and that the actual truth of the story is less disturbing than what’s being put on screen. And yeah, that’s usually the deal…but not always.

In these 17 frightening films based on actual events, some details may be embellished, but they hew close enough to the real incidents that telling yourself ‘it’s just a movie’ won’t be enough to stop your spine from tingling and your pulse from racing.

The 100

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