In October 1994, film students Heather, Mike, and Josh set out to produce a documentary about the fabled Blair Witch. They travel to Burkittsville, Maryland and interview residents about the legend. Locals tell them of Rustin Parr, a hermit who lived in the woods and kidnapped eight children in the 1940s.
On the second day, the students explore the woods in north Burkittsville to research the legend. Along the way, they meet two fishermen, one of whom warns them that the woods are haunted. He also tells them of a young girl named Robin Weaver who went missing in 1888. When she returned three days later, she talked about “an old woman whose feet never touched the ground.” However, his companion is skeptical of the story. The students then hike to Coffin Rock, where five men were found ritualistically murdered in the 19th century, their bodies later disappearing. The group then camps for the night.
On the third day, they move deeper into the woods despite being uncertain of their exact location. They eventually locate what appears to be an old cemetery with seven small cairns. They set up camp nearby and then return to the cemetery after dark. Later that night, they hear the sound of twigs snapping from all directions but assume the noises are from animals or locals. On the fourth day, they attempt to hike back to the car, but are unable to find it before dark. Much to their frustrations, they set camp. That night, they again hear twigs snapping but fail to find the source of the noises.
On the fifth day, they find that three cairns have been built around their tent during the night, which unnerves them. As they continue, Heather realizes her map is missing, and Mike later reveals he kicked it into a creek the previous day out of frustration, which prompts Heather and Josh to attack him in a rage. They realize they are now lost and decide simply to head south. They eventually reach a section where they discover a multitude of humanoid stick figures suspended from trees, which further unsettles them. That night, they hear sounds again, but this time includes the sounds of children laughing among other strange noises. When an unknown force shakes the tent, they flee in panic and hide in the woods until dawn.
Upon returning to their tent, they find that their possessions have been rifled through, and Josh’s equipment is covered with a translucent slime. As they continue, they begin to show signs of mentally giving up, and it is made worse when they come across a log on a river identical to one they crossed earlier. They realize they have walked in a circle, despite having traveled south all day, and once again make camp, completely demoralized at having wasted an entire day, their sixth. Josh suffers a mental breakdown while holding the camera, taunting Heather for their circumstances and her constant recording of the events.