Cracking the Father and Son safe code in Indiana Jones and the Great Circle is one of the first really tricky puzzles that you encounter in the game, and that's saying a lot when you find a new mystery to unravel every five minutes or so. This one appears in the Vatican after you save Giuliana during A Nun in Trouble and it'll require all of your critical faculties to solve.

Okay, that's a bit of an exaggeration, but it is fairly complex. You'll need to recognise a pattern on one sheet of paper and use it to decipher the safe code on another. To make matters worse, one of the pieces of information is literally wrong, so there's no way to reach the correct answer using the right method—don't ask me why. Either way, here's the Father and Son safe code in Indiana Jones and how you were supposed to get it.

How to get the Father and Son safe code

After you help Gina save Giuliana in A Nun in Trouble, she'll give you a key to a secret room in the Borgia Tower—the same place you just rescued her. You likely encountered this door earlier when you used the whip to swing across a gap to get behind a door blocked from behind. If not, head back down the tower until you spot the gap you can use your whip to swing over, with a door directly on the other side.

You can use Giuliana's key to unlock this door, which leads outside, and a second just behind it which leads into the Agency Room where the safe is located. Now to cut a long story short, the safe code is 5873. Simply input this on the dial to open it up and peruse the contents, solving the Father and Son mystery. If you want to know how I actually got that, I'll explain below.

In the Agency Room there are two desk drawers; one containing an Italian poem appropriately named 'Father and Son' which has a series of letters circled, and the other holds a Polybius Square Diagram, which is to say, a grid where two letters correspond to a number. What you need to do is take each pair of circled letters in order and input them into the grid to get the four safe code numbers. That means:

• I and R – 5
• I and A – 8
• T and A – 7
• S and A – 3

“Hold on a minute! S and A doesn't make 3, it makes 9?” You are correct, eagle-eyed reader; for some reason the last combination is wrong even though all the others are correct. I can't say why this doesn't work, but it might explain why you were struggling with the puzzle if you'd already worked out what you needed to do. Either way, input the above code and you'll have that safe cracked.