Egypt 1900. Egyptian archaeologist Eugene Dubois [Bernard Rebel] has been tied to some stakes and is being guarded by some Egyptians. More ride up on horseback. One looks through his clothes and belongings, takes out a knife, stabs him and cuts off his hand.His body is brought back to camp where his daughter Annette Dubois [Jeanne Roland] and Egyptian archaeologists Sir Giles Dalrymple [Jack Gwillim] and John Bray [Ronald Howard] are staying. The Egyptians warn them of the curse of Ra's tomb but the archaeologists dismiss it as superstition. Annette discovers the severed hand and the bloodied knife outside.The archaeologists and their aides remove Ra's sarcophagus from its tomb. They are informed that their financial benefactor Alexander King [Fred Clark] has arrived. Sir Giles and his Egyptian colleague Hashmi Bey [George Pastell] want the exhibits to be sold to the Cairo museum, but against their wishes King wants to take the exhibits on a world tour to make a lot more money. Sir Giles resigns in protest so King appoints Bray head of the exhibition and relics. That evening, while they discuss the curse of the pharaohs, the store room containing their relics is ransacked. One of the Egyptian servants has been murdered and their inventory list stolen suggesting others are interested in their findings.On board ship back to England, Annette and Bray discuss their futures on deck when a scream alerts them to a man attacking Sir Giles with a knife. The attacker also threatens Annette before another passenger Adam Beauchamp [Terence Morgan] intervenes, fights the attacker and knocks him off the ship into the sea. Beauchamp offers to keep Bray and Annette safe and help secure their Egyptian relics.In London, Bray and Annette invite Beauchamp to accompany them to see the relics where King is having them unpacked for exhibition. Annette tells Beauchamp the story of the pharaoh. Ra searched for eternal life but his father Rameses banished him to the desert. A tribe of nomads made Ra their king and gave him a medallion used in reviving the dead. Ra planned to return to his homeland for vengeance, but his brother sent assassins to kill Ra before he could leave. The assassins cut off Ra's hand to prove he was dead but did not take the medallion. King opens the sarcophagus to reveal Ra's mummified bandaged body [Dickie Owen].Back at Beauchamp's house, Annette tells Beauchamp about her relationship with Bray. Bray arrives and Annette takes a medallion out of her bag that she says her father gave her. Beauchamp shows an interest in it so they agree to have the medallion authenticated by Sir Giles, but after Bray insults Sir Giles he is left to try and identify the medallion alone. While he does so, he is attacked and knocked unconscious by an assailant who steals the medallion.King introduces the exhibition in London and tells the story of the archaeologists and how they found the tomb of Ra. Before opening the sarcophagus, King warns the assembled crowd of the curse of the pharaohs saying it will affect anyone present at the opening. But when the sarcophagus is opened, it is empty. Inspector Mackenzie [John Paul] from the police arrives to investigate but no-one can explain what has happened, although Bray speculates that someone may have stolen the body to bring it back to life, an idea that King disputes. As King leaves the exhibition that night he encounters the mummy in a narrow passageway. The mummy strangles King and pushes him into the river. Bray visits where Bey is staying in London and asks for his help.At home Sir Giles is examining Egyptian hieroglyphics and works out they refer to the sacred words of life, but just as he does the mummy crashes in through the French windows. He tries to shoot it but the mummy kills him by hitting him with a heavy ornament.At Beauchamp's house, Annette has fallen in love with him and decides to leave Bray. The mummy breaks in and starts to attack Beauchamp but when Annette screams, it approaches her instead. Beauchamp speaks to the mummy in Egyptian in an attempt to stop it but when it doesn't Annette faints. The mummy however gently strokes her, then returns to Beauchamp and knocks him out, then leaves. Bray, Bey and Inspector Mackenzie arrive and Bray convinces the Inspector to give them a second chance.While Bray discusses the curse with Bey the mummy breaks in, but it is a trap and the police catch the mummy in a net. Bey kneels before the mummy and offers himself as a sacrifice. The mummy breaks out of the net and crushes Bey's head with its foot before leaving without attacking anyone else, followed by the police. This proves to the Inspector and Bray that only those present at the opening of the sarcophagus are in danger, which still means Bray and Annette.At his house Beauchamp shows Annette his collection of Egyptian relics. Annette questions how he has his knowledge and Beauchamp reveals that he is Rameses's other son, cursed by Rameses to everlasting life, who can only die by the hand of his brother Ra who was killed by the assassins he sent. But now he has the chance for peace since he can die as Ra has returned to life. He places the medallion around Annette's neck and makes her repeat the words to awaken Ra's mummy. Before he can die he instructs Ra to kill Annette, the last of the tomb pillagers. Bray and the police burst in so Ra and Beauchamp take Annette into the underground tunnels. As they struggle with their pursuers to close the door behind them, Beauchamp's hand is trapped and severed as the door closes. However, Ra won't kill Annette because of her beauty. As Beauchamp takes out a knife to stab her himself, Ra stops him and forces him underwater, drowning him. The mummy leaves with the medallion and pulls down the roof of the tunnel on top of him, burying himself under a pile of stones and rocks, leaving Annette safe to be rescued by the police.