Dark Tunnel follows the life of a teenage girl who gets connected with an underground organization. This organization is both notorious and gruesome. They are heavy manufacturers of illegal substances and trafficking. She gets in over her head and begins to learn more and more about what they do and she fears they might catch on to her.

She goes through several personal ordeals as she faces abuse, struggle and guilt. These three issues build up inside of her and she has to cope with it. Only after certain events, does she feel the need to take action.