While exploring the ancient tomb of King Tutankhamen in Egypt, Professor Doug McCadden, of the California Institute of the Sciences, discovers a stone casket surrounded by several corpses, all of which appear to have had their flesh eaten away. Doug ships the casket to the Institute, where it is examined by a group of graduate students, including Susie Fuller, Doug’s personal assistant and lover, who translates the name on the casket as Ankh-Venharis, which means “Noble Traveler.” The lid of the casket is removed, exposing a hastily-prepared mummy covered with a powdery green substance, which the professor identifies as a dormant fungus. Later, student Peter Sharpe x-rays the casket, under the supervision of Chief Engineer Jack Parker, who halts the process upon realizing the machine is emitting ten times the necessary amount of radiation. When Peter examines the developed film, he notices a group of spherical objects positioned near the head, and upon searching the casket, discovers a compartment containing five crystals and a V-shaped metallic wedge. After stealing the crystals and replacing the wedge, Peter x-rays the head once again, using the same amount of radiation as in the previous photographs. He hides the original x-ray among the machinery in the Nuclear Reactor Complex, then delivers the second x-ray to Doug’s office. Doug shows Susie a drawing he found inside the casket, which she interprets as an astrological symbol. Neither can identify the material on which it is rendered. Meanwhile, Ankh-Venharis and the dormant fungus have been revitalized by the exposure to radiation. The next day, college president Dr. Wendell Rossmore holds a press conference to announce Doug’s discovery, and as the casket is positioned for public viewing, a student named Michael Goldstein touches the fungus and he is severely burned. Nevertheless, Rossmore proceeds with the conference. When they remove the casket lid and find it empty, Rossmore calls a meeting with Doug, Institute vice president Dr. Bruce Serrano, and Capt. Willoughby of the campus police. All assume the mummy was stolen by members of a fraternity, and offer twenty-four hour amnesty for its return. However, Doug reminds them of Michael’s injury and suggests involving the police. Fearing negative publicity, Rossmore dismisses the idea, and places Willoughby in charge of the investigation. Doug consults with Dr. Ken Melrose, who is mystified by the rapidly growing fungus. His colleague, Dr. Hayworth, comments on its ability to destroy tissue, and recommends amputation of Michael’s hand as the only cure for his condition. Unable to sell the crystals to a jeweler, Peter gives one as a gift to Sherri, his girl friend, and sells the others to fraternity brothers Greg Hauser, Bill Vogler, and Stanley Robinson, all of whom marvel at the stones’ pulsating glow. Greg visits his girl friend, Ellen Winters, while she is babysitting, and presents her with a necklace made from one of the crystals. However, when she responds to a strange sound from the baby’s room, Ankh-Venharis appears and removes the necklace, leaving a severe burn on her chest. Ellen is rushed to the hospital, where Doug, Melrose, and Hayworth discuss the case with police lieutenant Plummer. Inside the Reactor Complex, the mummy places Ellen’s crystal in the metal wedge, then charges it by joining a pair of power lines. The resulting electrical disturbance interferes with radio signals, causing telephones to ring spontaneously, and setting off automobile horns. At the hospital, Doug and Ken examine the mummy’s x-rays, and suspect that the creature may not be human. Doug discusses the contents of the scroll found inside the casket, which recounts the discovery of Ankh-Venharis in the Egyptian desert. Believed to be a god, the creature was welcomed to the court of Tutankhamen, resulting in the sudden demise of the king and his ministers. Soldiers sealed Ankh-Venharis inside the tomb, along with the deadly fungus, where it remained dormant for 3,000 years. Later, Stanley presents Susie with a crystal mounted on a bracelet, and though she accepts the gift, she remains faithful to Doug. Peter’s fraternity throws an Egyptian-themed party, and Bill brings his crystal, hoping it will attract a female companion. However, Ankh-Venharis appears and shoves Bill through a brick wall, instantly killing him. When police arrive at the scene, they determine that every bone in Bill’s body was broken. The next morning, Doug notices that sunlight refracted through Susie’s bracelet projects the same cryptic image found on the scroll. They consult with Jack, who identifies the image as a radio schematic. When Doug sends Susie to the astronomy center to research ancient phenomena, Ankh-Venharis follows her into the building and chases her to the roof. He removes the crystal without infecting her, but she is injured in a fall. While recovering in the hospital, Susie tells Doug, Jack, and Ken that Ankh-Venharis meant her no harm and was only interested in retrieving the crystal. Doug and Jack deduce that the crystals are required to power a transmitter, and upon discovering the missing x-ray, they question Peter, who reveals that the fifth crystal is at Sherri’s apartment, which she shares with Jack’s girl friend, Jenny. However, Jenny is in the shower when Ankh-Venharis arrives, and he recovers the crystal without incident. As Doug locates the transmitter in the Reactor Complex, Serrano, Rossmore, and Willoughby appear, blaming him for the missing mummy and the deaths of two students. Ankh-Venharis enters and places the final crystal in the transmitter. The room goes dark, except for the glow of the crystals, and the mummy’s wrappings disappear to reveal an extraterrestrial creature. Willoughby fires his gun at Ankh-Venharis, but Doug dives into the bullet’s path, and is wounded in the arm. The alien takes Doug’s hand and they disappear, leaving a single crystal on the floor. Serrano touches it and is severely burned.