In Deathloop, there's a lot to learn in and around Fia's bunker, but if you go in guns-blazing or otherwise set her off, she'll hit the panic button and cause an explosion, killing everyone. Therefore, you'll want to disarm the reactor stealthily, and that's a complicated process--but it wouldn't be Deathloop if it were simple, would it? Here's how to disarm the reactor on Fristad Rock.

Deathloop: How to disarm the reactor in Fia's bunker

You'll want to start off by heading to Fristad Rock at noon. Fia will be there in her bunker at that time, which means the doors will be unlocked for you to get in. It also means the place is crawling with Eternalists, so be very careful. You also won't want to be so direct, as you'll need a specific item with you, though if you play this level with the Aether Slab and either the Shift Slab or the double-jump Trinket, you can skip the next part, which details where to find a battery. You won't need it if you have those items.

If you do need the battery, head out of the tunnels and under the bright, fallen electronic sign to your right. Continue along the path, avoiding or disarming traps along the way, including landmines and tripwires. Take a left up the hill to the Transmission Post--the circular stone building. Avoid the guards inside and descend the cliffside, dodging (or killing, it's up to you) more Eternalists outside the bunker's alternate entrance. This is where you'll also get the delivery booth code, FYI.