Severed

On a forested, remote island, Mac leads a team of loggers while Rita's eco-protesters oppose the operation. The company’s chemist Carter runs an experiment in the area, promising faster profits. A logger is wounded by a spiked tree, and sap from the tree begins to infect the wound, setting the outbreak in motion.

The wound festers as the sap mutates the logger’s biology, hinting at a rapid transformation. As protests continue, fear spreads among the workers and protesters alike. The seed of the zombie outbreak has taken hold.

The company president sends his son Tyler to investigate the loss of contact with the loggers and to learn more about the incident. Upon arrival, he discovers that most of the loggers and protesters have become zombies. He finds a bunker shelter where Mac, Rita, Carter, Luke, and other survivors have holed up.

A company chemist examines a sample from Carter and becomes infected, confirming that the sap-altered mutation is spreading. The board overrules the president’s plan for evacuation, deciding to quarantine rather than leave the island. The outbreak now has a corporate-backed cover, complicating rescue efforts.

The survivors attempt to drive off the island in a bid for safety, but the company blocks the road with armed support. The group becomes separated in the chaos, and more members fall victim to the advancing zombies as they try to escape. The bunker’s sheltering walls offer no guarantee of safety.

The survivors regroup at the logging base and Mac manages to secure another truck. They decide to drive to an abandoned facility to attempt radio contact for help. The plan is to reach a remote facility that may pick up a distress signal.

Back at the camp, the radio proves dead during diagnostics. Meanwhile, Tyler and Rita grow closer as they bond under stress. Luke is dragged off by the zombie horde when Carter, frightened, fails to intervene.

Carter reveals to survivors that the company funded genetic experiments to accelerate tree growth, increasing profits but triggering the outbreak. The revelation compounds guilt among the survivors, especially as the situation grows more desperate.

The group pushes toward another exit but encounters more zombies along the road. Mac discovers Luke is now a zombie and kills him with an axe, a sorrowful blow he shares with Rita. A helicopter approaches but opens fire, showing that rescue may not come from above; a renegade band of loggers intervenes.

The survivors are brought to a renegade, militaristic camp where a sadistic game requires killing a number of zombies in a pen. The head of the camp tries to rape Rita, prompting Tyler to defend her, and the two acknowledge a mutual attraction that leads to a late-night tryst.

Carter is selected to enter the zombie pen but is overwhelmed by fear and jams his gun, needing rescue. The other loggers mercilessly bully him for his failure, worsening his already fragile psyche.

In a spirit-crushed state, Carter leaves the camp at night with an axe. Zombies flood the open gate and slaughter most of the camp, forcing Mac, Rita, and Tyler to flee. Mac is bitten in the chaos, foreshadowing the tragedy to come.

At the gate, Mac is bitten and begins to turn, and Rita confesses that she was the one who spiked the tree, asking his forgiveness as he dies. Tyler and Carter try to save Carter but are overwhelmed by the surrounding zombies. Rita, now the last survivor, follows the road by the car lights in hopes of escape, while Tyler’s father back home realizes his actions sealed their fate.