Indiana Jones and Dr. Marcus Brody are summoned to an apartment in New York. While there, Indy checks his mail and mysteriously finds his father`s diary about the Holy Grail. Walter Donovan arrives and shows them a tablet he has found. Indy and Brody say they no nothing about it and Donovan gives them airplane tickets to Venice, Italy. There, they meet Dr. Elsa Schneider who leads them to a library. On the way, they are suddenly attacked by mysterious men. As they enter, Indy builds an X on the floor and drops a chandelier on it, revealing a passageway to an underground cavern. Brody refuses to enter, so Elsa and Indy explore it, avoiding various obstacles. They discover a knight`s skeleton with an exact replica of the tablet Donovan showed Indy and Brody earlier. They learn that this is a clue to finding the Holy Grail! Suddenly, the men that attacked them return, knock out Brody and set the cavern on fire. Indy and Elsa escape and chase the brutes` head honcho, Kazim, in motor boats. After stranding him near a boat`s active propeller, Indy, Elsa, and Kazim escape being shredded to bits. In gratitude for saving him, Kazim tells Indy that his father is being held captive at Castle Bruwald in Germany. Indy and Elsa set off to rescue him.