Grim

A member of the friend group whose curiosity during the seance allows the Grim to inhabit her. She wrestles with the creature’s control while remaining determined to protect her friends. Her arc blends fear with resilience as she fights to break free from possession and aid in the group's plan. Her experience shows how normal curiosity can lead to extraordinary peril in the presence of ancient evil.

Katie's loyal friend who acts as the group’s pragmatic voice early on but is overwhelmed by the Grim in the tunnels. He embodies courage under pressure and becomes a casualty that heightens the group's urgency. His death marks a turning point, deepening the resolve of Rob and the others to rescue the captives. He embodies the cost of confronting the supernatural threat.

One of Katie's friends who is killed by the Grim in the cave sequence. Her loss underscores the real danger of the supernatural force and raises the stakes for the survivors. Her absence amplifies the group's sense of vulnerability and urgency. She symbolizes the immediate toll of the encounter with the entity.

A member of the spelunking crew who is abducted by the Grim and taken to its lair. Her capture drives Rob to assume leadership and push the rescue mission forward. Her fate becomes a catalyst for the group’s coordinated effort to outmaneuver the creature. She represents the vulnerable, who are pulled into the danger from the shadows below.

An official familiar with the tunnels who organizes the impromptu spelunking crew. He demonstrates steady leadership, tactical thinking, and a willingness to risk himself to save others. His knowledge of cavern layouts helps the team identify the Grim’s vulnerability to bright light. He anchors the group’s plan and remains committed to a rescue mission.

Rob's former sweetheart who joins the mission, providing emotional grounding and practical support. She endures trauma alongside the others and helps drive the rescue effort. Her resilience and loyalty become crucial as casualties mount and the group fights to survive. She embodies strength in the face of sprawling horror.

A woman abducted by the Grim and kept in its lair; her mental state deteriorates under the creature’s influence. She becomes a symbol of the town’s hidden dangers and a key motivation for the rescue effort. Her fate remains uncertain as the protagonists escape and the cave’s horrors linger beneath the surface.

One of the abductees who dies during the escape sequence, adding to the mounting casualties faced by the survivors. His death reinforces the peril of the Grim and the price of attempting to free others. His loss intensifies the group’s resolve to complete the mission for those left behind.

A member of the group who falls under the Grim’s possession and becomes insane. She is left behind by the rescuers due to her precarious state, highlighting the limits of the team’s ability to save everyone. Her condition illustrates the broad human toll when a community confronts an otherworldly threat.

The primary antagonist—a supernatural entity imprisoned in underground caves that can possess and manipulate the living. It travels beneath Woodland Hills to attack animals and abduct people, seeking freedom. It is vulnerable to bright light, a weakness the protagonists exploit to trap it again. Its presence drives the horror and catalyzes the town’s nightmarish unraveling.

Mary's husband appears in the cast, hinting at a domestic life beyond the crisis; the summary provides little detail about his role, but he represents the ordinary life that the horror intrudes upon. His presence underscores the personal stakes and the disruption of everyday existence caused by the supernatural threat.