Who finds mutated men who attempt to kill them?
Dr. Edwards arrives at a secluded island laboratory to examine Mr. Porter. Although Porter carries a deadly flesh-eating virus, he is asymptomatic and shows no signs of necrosis. Along with fellow researchers Camila and Bridget, Dr. Edwards spends two months examining Porter in isolation. Porter continually asks to see his wife, but he is continually denied.
Marcus prepares to marry wealthy heiress Kate Arias in the Dominican Republic. Mark's best friend Dobs, his brother Josh, and Josh's girlfriend Penny charter a boat and take Mark to a supposedly unpopulated island for a low key bachelor party.
Sympathetic researcher Camila creates a rapport with Porter. Frustrated with his confinement, Porter intentionally infects one of the researchers as he begins revolting against his continued isolation. Porter warns Camila that he is dangerous. Bridget becomes infected.
Josh and Penny go snorkeling and find dead sea animals littering the ocean floor. When they return to camp, Josh and Penny discover strange rashes on their skin. While Josh performs oral sex on her, Penny begins spitting up large amounts of blood and her flesh starts melting. Josh radios for help and a voice claiming to be Dr. Edwards provides him with instructions.
Realizing that they need help but are stranded, Mark and Dobs search the island and find a bunker. Inside, the two friends discover research related to the virus. They also find mutated men who attempt to kill them. Mark and Dobs are able to escape the human danger, but Dobs becomes infected.
The bunker turns out to be connected to Dr. Edwards' laboratory. Josh reunites with Mark and Dobs and they find the researchers. After formulating a plan for extraction, Bridget and Josh split off to gather Penny and wait for the boat on the beach. Dobs and Edwards also go on their own while Porter, Camila, and Marcus initiate the laboratory's self-destruct sequence.
Mark Dobs