In 1936, American archaeologist Indiana Jones braves an ancient booby-trapped temple in Peru to retrieve a golden idol. He is confronted by rival archaeologist René Belloq and the indigenous Hovito people. Surrounded and outnumbered, Jones is forced to surrender the idol to Belloq but manages to escape aboard a waiting seaplane.
Two Army Intelligence agents later interview Jones at Marshall College, where he holds a teaching position, and inform him that the Nazis are working with his old mentor, Abner Ravenwood, whom Jones studied under at the University of Chicago. The Nazis know that Ravenwood is the leading expert on the ancient city of Tanis in Egypt, and that he possesses the headpiece of an ancient Egyptian artifact known as “the Staff of Ra”. Jones deduces that the Nazis are searching for the Ark of the Covenant, believing it will grant their armies invincibility. The agents authorize Jones to recover the Ark.
He travels to Nepal to discover that Ravenwood has died and the headpiece is in the possession of Ravenwood’s daughter Marion. Jones visits Marion at her tavern before a group of thugs arrive with their Nazi commander Arnold Toht, seeking the headpiece. A gunfight erupts, the bar is set ablaze and the headpiece lands in the flames. Toht severely burns his hand trying to retrieve it and flees the bar in agony. Jones and Marion escape with the headpiece, and Marion decides to accompany Jones in his search. They travel to Cairo, Egypt, where they meet up with Jones’ friend and skilled digger Sallah. He informs them that Belloq and the Nazis are digging for “the Well of Souls”, believed to lead to the Ark’s location, with a replica of the headpiece created from the scar on Toht’s hand. Jones and Marion are attacked by a group of Nazi soldiers, and Marion is seemingly killed in an explosion during the resulting chase. Jones regroups with Sallah, and they realize that the Nazi headpiece is incomplete and that the Nazis are digging in the wrong place, as they only have part of the information regarding the Well’s location.
After a confrontation with Belloq in a local bar, Jones and Sallah infiltrate the Nazi dig site. Jones finds Marion alive, bound and gagged in a tent; he does not set her free in fear of alerting the Nazis, but promises to come back for her later. Jones and Sallah use their staff to locate the Ark in the snake-infested Well of Souls. Belloq, Toht, and Nazi officer Colonel Dietrich arrive and seize the Ark from Jones, before imprisoning him and Marion in the crypt. The two escape to a local airstrip, where Indy gets into a fistfight with a mechanic and destroys the flying wing that was to transport the Ark to Berlin, Germany. The panicked Nazis load the Ark onto a truck, but Indy manages to catch up on horseback, hijack the truck, fight off the Nazis, and make arrangements to transport the Ark to London aboard tramp steamer Bantu Wind. In the cargo hold, an unseen force burns the Nazi symbols painted on the wooden crate containing the Ark.
The next day a Nazi U-boat intercepts the ship. Belloq, Toht, and Dietrich seize the Ark and Marion but cannot locate Jones, who stows away aboard the U-boat and travels with them to an island in the Aegean Sea. Once there, Belloq plans to test the power of the Ark before presenting it to Hitler. Jones reveals himself and threatens to destroy the Ark with an anti-tank rocket, but Belloq calls his bluff and Jones surrenders.
The Nazis take Jones and Marion to an area where the Ark will be opened and tie them to a post to observe. Dressed as an Israelite kohen gadol, Belloq performs a ceremonial opening of the Ark by invoking a standard Sabbath prayer, and finds it full of sand, possibly all that is left of the Ten Commandments. As Jones warns Marion to keep her eyes shut, spirits emerge from the Ark, eventually revealing themselves to be angels of death. Flames then form above the opened Ark and bolts of energy shoot through the gathered Nazi soldiers, killing them all. In the extreme heat, Dietrich is instantaneously mummified; all the flesh on Toht’s face melts off his skull; and Belloq’s head explodes. Flames then engulf and vaporize the remains of the doomed assembly, save for Jones and Marion, in a whirlwind of fire before the Ark seals itself shut. Jones and Marion open their eyes and find the area wiped clean along with their ropes burned off, and embrace.
Back in Washington, D.C., the Army Intelligence agents inform Jones and Marcus Brody that the Ark is someplace safe and will be studied and monitored by “top men”. It is then shown being sealed in a wooden crate and stored in a giant government warehouse among countless other crates.