Mahmoud is searching for an Egyptian jewel called 'The Eternal Light', which is alleged to bring immortality to the person in possession of it. He arrives at the house of Dragore, who originally stole it from Egypt. Dragore informs him that he sold it to a Professor Morlant, who has only a few days to live.

Morlant implores his servant, Laing, to bandage his hand up around the jewel, so that when he dies he will be able to present it to the idol Anubis and gain immortality. Morlant is buried according to his wishes, but Laing sneaks into the tomb and steals the jewel. Broughton, Morlant's accountant, suspects Laing and follows him.

Morlant's heirs, Betty and Ralph, gather at his mansion to claim their inheritance, and are told about 'The Eternal Light'. The local parson, Nigel Hartley, joins them under the pretence of offering comfort after Morlant's death, as does Dragore, who joins Betty's maid, Miss Kaney, in the hunt for the jewel.

Laing returns to the tomb at midnight, and to his horror sees Morlant rise from the grave. He runs in fright back to the mansion, where he discovers that Betty has unknowingly pocketed the jewel. Laing prays for forgiveness, but is interrupted when Morlant breaks the iron bars on the window and enters the room. Morlant begins to strangle him, but Laing directs him to Betty, and is released.

Morlant finds Betty, attacks her and retrieves the jewel. He leaves to make his way back to the tomb, and Ralph discovers Betty, who has fainted. Ralph and Betty start to follow Morlant. Unknown to them, Dragore is also in pursuit.

With Ralph and Betty watching from the sidelines, Morlant performs the ritual, slashing his chest with a knife, and placing 'The Eternal Light' on the hand of the statue of Anubis. The hand closes around the jewel, and Morlant dies, believing the prophecy to have come true. However, the hand belongs not to the statue but to Hartley, who is in reality not a parson but a petty thief.

Ralph confronts Hartley and knocks him unconscious, but Dragore arrives at the tomb with a gun, and gets Ralph to hand the jewel over to him. Dragore closes the door of the tomb as he leaves, trapping Ralph, Betty and Hartley inside. Unfortunately, a stray bullet from Dragore's gun has dislodged the torch suspended over Morlant's coffin, and as he closes the door, it falls, setting fire to the tomb.

Dragore runs from the scene, but bumps into Kaney. She inadvertently knocks the jewel to the floor, and then manages to run away with it. Broughton arrives in his car and stops Dragore, and together they go after Kaney. She holds the jewel over a well, threatening to drop it, and stalls them long enough for the police to arrive.

The police arrest Broughton and Dragore, and Kaney hands 'The Eternal Light' over to them before fainting. It is revealed that Morlant's 'resurrection' was not due to supernatural forces, but that he was buried alive.

Back at the tomb, the fire from the torch ignites the fuse to an explosive that was placed there by Hartley previously. The door is ripped open in the explosion, and Ralph carries Betty out to safety.