Synopsis (contains spoilers)Edit
Shortly before World War II Steve Fisher, an Englishman, accompanies a Swedish archeological expedition to an Egyptian tomb. They discover a room full of treasure, with an emblem on the wall depicting the eye of the sun god Ra: a warning to grave robbers. Although the archeologists agree to keep their discovery a secret one member of the expedition, Gunnar Hansonn, offers to give away the location of the tomb to a shady antiques dealer named Aziz El-Kasim for the right price.
That night, Steve Fisher is murdered by an Egyptian with a sword tattoo on his arm; with his last words, he mentions 'the sign of the sword' to some passing British officers. The killer escapes and reports to his leader, the antiques dealer Kasim, who is also the leader of an anti-British organisation named the Brotherhood of the Sword. Kasim makes a deal with a German agent named Otto Frisk: in return for the artefacts in the tomb, Frisk promises Kasim arms, as both men hope to drive the British from Egypt.
Years later, following the outbreak of the war, Steve Fisher's younger brother Alan joins the army and is posted to Egypt. En route to Cairo Alan and his comrades are attacked by members of the Brotherhood of the Sword; the Egyptians are defeated, and the sole survivor of their band is kept as a prisoner. Alan notices the man's sword tattoo and wonders if there is a connection to the murder of his brother.
Alan is subsequently transferred to a transit camp under a new name, the idea being that he can infiltrate the Brotherhood by pretending to betray the British army. He succeeds and joins Kasim, Frisk and Hansonn on a mission to ship some gold from Cairo; during this expedition they accidently crash their jeep into a rock. Two mechanics who happen to be passing by with a British officer are unnable to fix it, and so Kasim, with the intention of stealing their vehicle, shoots them dead and takes the officer captive. Alan is outraged, although Kasim still believes him to be on the side of the Brotherhood.
In the night, Alan frees the captive officer and makes it look as though he freed himself following a struggle. Hansonn is sent to capture him, and comes back reporting that the man died.
The band reaches its destination, an oasis, but after collecting the gold is ambushed by British soldiers led by Captain Scott, Alan's superior. Most of the Egyptians are defeated, but Kasim, Frisk and Hansonn escape with the gold; against the orders of Scott, Alan gives chase in an abandoned jeep.
As Kasim and his band flee, they realise that the escaped officer did not die, and must have warned Scott. Hanson admits that he merely assumed that the man would die of thirst; as punishment, Kasim abandons him in the desert. He is found by Alan and claims that he was working for Kasim unwillingly. Alan believes this and takes Hansonn with him.
When the two men reach Kasim, Frisk and another Brotherhood member named Abdul at the tomb, Hansonn knocks Alan out with a rock and rejoins the Brotherhood; he is forgiven for his earlier failure. As Frisk feels that Alan will be useful to the Gestapo, he is kept alive and taken into the tomb. Seeing the remains of the Swedish expedition, he realises that Kasim was responsible for his brother's death. Abdul, in a panic brought on by the alleged curse of Ra, flees and is shot dead by Frisk. Alan, in the confusion, grabs a bayonet and kills Frisk with it before escaping into the corridors.
Hansonn decides to escape the tomb before things get worse and threatens Kasim with a grenade; Alan, watching from behind, throws the bayonet at Hansonn and kills him, causing him to drop the grenade. Kasim is killed in the blast, but Alan escapes and is picked up by Captain Scott, who had found out about the tomb from an Egyptian captured at the oasis. The men return to Cairo with Kasim's gold.