PHOENIX — On March 13, 1997, thousands of people across Arizona reported seeing strange lights moving soundlessly through the sky.

It became one of the most famous UFO sightings in history and, 20 years later, will be the focus of a new found-footage horror film set to be released this year.

“Phoenix Forgotten” tells the story of Sarah Bishop, a documentary filmmaker who returns to Phoenix 20 years after her brother disappeared investigating the Phoenix Lights.

While the plot is murky, it seems Bishop will come across a video recorded by her brother and two others about their experiences investigating the lights. The found-footage style of film was first popularized by the cult hit “Blair Witch Project.”

Phoenix Forgotten is scheduled to be released April 21. It hasn’t been given a rating, but we’re guessing, based on the trailer, that it will be rated R.

While the film will be more fiction than fact, the Phoenix Lights phenomenon still captivates people to this day.

Dr. Lynne Kitei with the Phoenix Lights Network said the mystery remains unsolved even though though the military tried to explain it.

“The military tried to explain it as flares five months after the event,” she said. “Some people saw the mile-wide craft glide over their heads at rooftop level silently. Some saw it take off at lightning speed. Some people saw orbs detach from the main object.”

UFO sightings are fairly common in the Phoenix area. At least once per year there are reports of strange lights in the desert sky.

According to a 2014 Washington Post article, Arizona has the highest number of UFO sightings per capita in the country.

KTAR’s Jim Cross and Taylor Kinnerup contributed to this report.

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