In a covert biological weapons laboratory somewhere in the Philippines, a group of scientists are working on a serum called Death One, which reanimates the dead. When Dr. Alan Holder and his assistant Norma experiment on a deceased human test subject, the corpse becomes reanimated and reacts violently, prompting Dr. Holder to resign from the project. As he prepares to surrender the serum to waiting military officers, a small group of criminals ambush the center; all but one are killed, and the surviving criminal manages to abscond with Death One. During a chase the container with the serum is breached by gunfire; as he tries to pick it back up, he accidentally touches the serum and is infected. He flees to the Sweet River Resort and settles in Room 4. General Morton promises Dr. Holder that he and his men will capture the criminal. By the time the soldiers catch up to him, however, he has already succumbed to the disease, but not before infecting a bellhop and killing a maid before finally cutting off his own hand in a failed attempt to stop the necrotizing spread of the infection. Morton orders the patrons and staff killed and buried in a mass grave and condemns the resort; the criminal's remains are delivered to him and his two right-hand men, Sergeants Tracey and Cheney, and later incinerated in a crematorium. As Dr. Holder and Norma fear, the ashes quickly disperse into the air, infecting an entire flock of birds passing by.