What is the name of the diary used by Indy to find the Holy Grail?

The diary Indy uses to find the Holy Grail is called the Grail Diary. It is a research journal compiled by his father, Henry Jones Sr., who spends years studying the Grail’s history, clues, and hidden route.

The diary becomes essential in Indiana Jones and the Last Crusade after Henry is kidnapped while investigating the Grail. It contains notes, drawings, translations, and a map showing the path toward Alexandretta, the modern Turkish city of İskenderun. Indy uses the information to follow the Grail trail through Venice, Austria, and the Middle East.

The Grail Diary is sometimes confused with the Map Room, which is a location in Raiders of the Lost Ark, or with the Crystal Skull from the later film. The diary also helps Indy interpret the clues and traps inside the Grail temple, including the warning that only one of the many cups is the true Grail. Elsa Schneider eventually steals it, but Indy recovers it in Berlin.