Your goal is to reach the Brain Scorcher lab which lies to the north-west. You basically have two ways to get there - either through the forest or by following the road. The first way will allow you to avoid the majority of Monolith in the central area which also means that you'll get little loot going this way. Following the road will mean that you have to defeat a number of Monolith soldiers, but you'll be able to pick up a lot of loot, including a fair amount of ammo for the SVDm-2 and SVUmk-2. I guess you can go through both areas and comb the entire are if you wish. The fastest way to the Brain Scorcher though is through the forest. I have included descriptions for both ways so you can read through them and see if there are any special items you can acquire by taking one route instead of another. However, before you can make the choice, you'll need to move onwards from the starting point in Red Forest.
Short after the entrance you'll notice a control point up ahead. There are about four Monolith soldiers ahead, so proceed with caution or just take them out from long range if you brought eg. the Vintar BC. Inside the small building you can find two medkits and a metal box containing some ammunition.
Moving on you should soon notice a dead stalker on the left side of the road, and probably one or more enemy PDAs in the vicinity. Right after the dead stalker you'll notice some very large rocks. Behind those rocks, and up the hill to the left is a Monolith sniper so be sure to lean out from cover and take him down. Also be sure to watch the road ahead since there are Monolith soldiers in that direction as well (some of which you may have already encountered and possibly taken down). There is a PSZ-9d Duty armour next to the sniper up the hill; also be sure to loot him of the rare 7.62x54mm 7N14 ammo and beware of the radiation (and possibly his dropped SVUmk-2 sniper rifle if you'd like). Once you've dealt with the enemies in the vicinity, it's time to decide which way you wish to go: either through the forest or along the road.
Following the roadEdit
Continue along the road - there are more soldiers ahead, along with another sniper located on the northern side of the road. Once you've taken care of them move on and you'll soon spot an APC further down the road. There is a truck behind it that has a sniper sitting in the back, and more Monolith soldiers in the vicinity. Once you've dealt with them continue on until you notice a large truck in the distance. Close by is a Monolith soldier wielding a RPG, and there is a sniper in the tower behind him - be sure to take out the guy with the RPG first since he by far poses the biggest threat. There are also about 4-5 other Monolith soldiers around so be sure when you approach the area. There is a gray caravan blocking the road going north, near the tower. Inside it you can find a Berill-5M Armored Suit, which by now really isn't much of an armor - it does have a high bullet protection, but rather low protection against everything else; I'd say that you're better off with the PSZ-9d Duty Armor you found earlier.
Feel free to make a small detour following the road to the north - it ends in a small installation (or control point) with more Monolith soldiers around. There are really nothing of importance here, except for a blue box and a hidden stash - but don't bother checking the latter if you haven't found the information about it.
Moving further to the west you should soon see another large truck on the left side of the road. About 70 meters behind it are more Monolith soldiers, including yet another sniper sitting in the back of a truck. When you finally make it to the truck with the sniper in the back, take a peek further to the west; you'll notice the fence coming to an end and the road moving further. Right where the fence ends you'll notice a tree - obscured by the tree, sitting atop a ledge is another sniper; there are also more Monolith soldiers near the construction materials. Deal with them and proceed west. You've completed this path, so skip the next section and move on to the final one.
Going through the forestEdit
Going through the forest poses the smallest threat and for the most part there are no Monolith soldiers to deal with until you reach the other side. You may encounter some anomalies, pockets of radiation, some Snorks and zombified stalkers, and if you're really lucky a Bloodsucker as well. All you need to do is basically follow the rocky edge to the west and to the north. On the way you may be able to find a Goldfish near 3 or 4 Springboard anomalies. Moving on you'll soon come to a fence with three dead scientists near it. There is a hole in the fence so use that to proceed but be aware that there is a Monolith sniper at the top of the ladder to the west (right on the other side of the second fence). Also there are Monolith soldiers ahead - near the construction materials on the other side of the second fence. Make sure you deal with them before you proceed. You can find a door and a keypad where the sniper is - the code for the door is 1287975 (thanks to Jeff/jarnold!). Unfortunately there isn't alot to be found behind the door; I personally only found 3 medkits. Once you've looted everyone along with the room, move up to the road and proceed west.
On to the Brain Scorcher facilityEdit
If you look at your map you should see a marker indiating the entrance to the Brain Scorcher lab (aka. X-19); it's a bit misleading because the entrance actually underground and not on the hillside as it would seem.
When you head up the road going west you'll soon see the first apparition - these are ghost-like figures resembling various known creatures, such as boars and bloodsuckers. The apparitions won't hurt you though, just slightly blur your vision if they hit you. You can shoot them to make them disappear but since they are only a slight annoyance you might as well save your ammunition. Soon you'll have your first PDA being registered on your minimap - it's another Monolith soldier close to some barrels - you may be able to spot the barrels before the soldier spots you, so shoot the barrels to have them explode - which will likely deal with the soldier. The same goes for another batch of barrels up the road - if you can spot them in good advance, rinse and repeat; if the soldiers spot you, otherwise, the barrels will be pushed down the hill and be a potential threat to you.
Soon after you'll spot a wall on the right side of the road - move up there, and stay behind the wall. The area ahead is the Brain Scorcher facility, and it has towers with snipers near the outer walls. Lean around the corner and you should be able to spot them; there are only snipers in the first two towers. Once you've dealt with them continue along the road - beware though because there is another sniper ahead, on the road next to a truck (at the point where the road turns from going south to west). You may at this point have alot of enemy PDAs in your vicinity - most of them should however be inside the facility walls and won't pose a threat to you just yet. Keeping following the road, initially moving on south and eventually turning west. You'll find the entrance to the outer perimeter there. When you enter the outer perimeter, the Turn off the Brain Scorcher mission will be updated and you now need to find the actual entrance to the inner facility.
Just inside the entrance you'll find a number of caravans. Inside one of them you can find a Guardian of Freedom Suit - it has the same protection values as the Duty Armor except for a higher explosion and impact protection, so you may wish to drop the latter and pick up the Guardian instead. To the north of the initial caravans is another caravan, next to an Electro anomaly; inside you can find two Monolith Suits along with three medkits and two antirads.
Slightly northeast of the first caravans you'll notice a train car with a ramp leading up into it. You'll find the entrance to the facility this way. Entering the car you'll see that it opens up into a tunnel. The tunnel has three Monolith soldiers in it, so proceed with caution. When you enter the tunnel your mission will once again be updated and you've reached the final goal: Deactivate the machine. Move to the end of the tunnel and beyond and you'll go to the Brain Scorcher facility.