For the most part, the missions in Far Cry 6 are nice and simple, but every now and then you're asked to find a hidden item. If you're struggling, here's a guide on where to find the prison key to free Miquel in Far Cry 6.
You'll need to free Miquel as part of the Operation called 'Second Son', which is part of the Montero family series of missions in Far Cry 6.
Where to Find Prison Key to Free Miquel in Far Cry 6
While looking around the outpost, you'll find a locked prison cell door that needs a key to open. This is where Miquel is being held.
Now, unlike in other missions, the key to the door isn't being held by an enemy or officer you're looking to kill. Instead, it is held in a room in a different part of the compound.
If you head to the upstairs section of the main building, you can then look to the back side of it, where you'll see two green lights. One is the alarm that you may have already disabled, and the other is a camera.
If you've not already cleared out the area, you may have to disable these two things as well.
Then, all you need to do is head inside that room where the green lights are and the key to the prison cell will be sat on a table.
Grab it and you can return to Miquel's cell to let him out. Be warned, though, the missions gets a bit chaotic after this, as enemies swarm you as you try to escape.
Miquel can hold his own, though, so don't worry about him too much. Just focus on taking out all the bad guys you can, or grab a car and hightail it out of there. It's up to you.