The Father and Son safe code in Indiana Jones and the Great Circle is 5873. The safe puzzle sits in a locked room near Borgia Tower in the Vatican. You get in by completing the A Nun in Trouble fieldwork and using Giuliana’s Key, then solve the clue with two in-game documents: the Italian Poem and the Polybius Square Diagram.
Where the Father and Son puzzle is and what unlocks it
The puzzle is in a room by Borgia Tower in the Vatican. Two sources describe the same access path: a GameSpot puzzle guide published December 6, 2024, and an Indiana Jones and the Great Circle wiki page on Vatican mysteries, dated May 17, 2026. Neither source names a platform or game patch version, so if the room or documents look different on your copy, check your version before assuming the path has changed.
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According to GameSpot, the A Nun in Trouble quest runs through the Museum Wing and Borgia Tower. Rescuing Giuliana earns Giuliana’s Key, which opens the locked room.
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- Start or finish the A Nun in Trouble fieldwork. Work through the quest in the Museum Wing and Borgia Tower until you rescue Giuliana.
- Collect Giuliana’s Key. The reward for the rescue is the key you need for the locked room.
- Return to the locked room near Borgia Tower and open it with Giuliana’s Key.
- Search the drawers for the Italian Poem and the Polybius Square Diagram. The poem contains circled letters. The square assigns digits at the points where its row and column labels meet.
- Decode the circled letters in pairs, convert each pair to a digit using the square, and enter the four-digit result, 5873, into the safe.
How the letter pairs become digits
The method works in three moves. Read the circled letters two at a time, in the order they appear in the poem. For each pair, find the first letter among the row labels and the second among the column labels on the Polybius Square, then take the digit where that row and column meet. Repeat for every pair; the four resulting digits are the combination. A video guide description summarises the same paired-letter, square-based method, which matches the GameSpot walkthrough.
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- STANDARD EDITION CONTENT — Includes the Indiana Jones and the Great Circle base game.
- BECOME INDIANA JONES — Play as the famed archaeologist in a first-person, single-player adventure set in 1937, between Raiders of the Lost Ark and The Last Crusade.
- A WORLD OF MYSTERY — Travel from Marshall College to the Vatican, Egypt, and Sukhothai as you investigate an ancient power, meet intriguing characters, and solve riddles.
- WHIP-CRACKING ACTION — Use Indy’s trademark whip to distract, disarm, and attack enemies, swing over patrols, and scale walls. Combine stealth, melee combat, and gunplay to face the enemy threat.
- THE SPIRIT OF DISCOVERY — Move between linear, narrative-driven gameplay and open-area maps as you uncover secrets, avoid deadly traps, and solve fiendish puzzles.
The one clue mismatch to know about
GameSpot’s transcription of the poem’s final circled pair reads S-A. On the square, that pair would produce 9. The accepted final digit is 3, which GameSpot’s own description ties to S-O. The guide suggests either a mistranslation or a bug, but it does not establish which, and no other source reviewed explains the difference.
In practice, this means the code to enter is 5873. If your own reading of the last circled pair gives a different digit than the one the square yields for the pair you see, recheck the letters you have circled against the poem in your game before concluding the code is wrong. Do not assume a bug; the evidence does not establish one.
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- YOU ARE INDIANA JONES – Live the adventure as Indy in a thrilling story full of exploration, immersive action, and intriguing puzzles. As the brilliant archaeologist – famed for his keen intellect, cunning resourcefulness, and trademark humo
- A WORLD OF MYSTERY AWAITS – Travel from the halls of Marshall College to the heart of the Vatican, the pyramids of Egypt, the sunken temples of Sukhothai, and beyond. Forging new alliances and facing familiar enemies, you’ll engage with intriguing characters, use guile and wits to solve ancient riddles, and survive intense set-pieces.
- WHIP-CRACKING ACTION – Indiana’s trademark whip remains at the heart of his gear and can be used to distract, disarm, and attack enemies. But the whip isn’t just a weapon, it’s Indy’s most valuable tool for navigating the environment.
- THE SPIRIT OF DISCOVERY – Venture through a dynamic mix of linear, narrative-driven gameplay and open-area maps. Indulge your inner explorer and unearth a world of fascinating secrets, deadly traps and fiendish puzzles
What the sources confirm
- The safe code is 5873, confirmed by the GameSpot guide and the wiki page.
- Access depends on the A Nun in Trouble fieldwork and Giuliana’s Key, confirmed by both.
- The two documents are the Italian Poem and the Polybius Square Diagram.
- The wiki page confirms the code and the prerequisite but does not discuss the letter mismatch.
The Indiana Jones and the Great Circle wiki Vatican mysteries page is at indianajonesandthegreatcircle.wiki. The GameSpot guide is at gamespot.com.
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