There's Something Wrong with the Children

Margaret and Ben take a weekend trip with longtime friends Ellie and Thomas and their two young children (Lucy and Spencer). They stay at a campsite and plan a night of drinking and telling stories about each other. The next morning, everyone hikes through the woods and come across an old building with a cave. Lucy and Spencer are drawn to a well in the cave, seeing a green light that none of the adults seem to notice. They return to camp and Margaret offers to watch the kids while Ellie and Thomas go on a romantic date. The children express a strong desire to return to the cave, but Margaret and Ben do not allow them to leave.