Inferno

Sidorovich is asking you to investigate the recent disappearance of Chemist and Fistful. Their last known position was Forgotten Forest, from where they reported to have found an Inferno artifact. The only lead is Cross, a local stalker.
== Walkthrough ==
You likely need a sniper rifle for this quest. Talking to Cross is not advised until you have one. If you want to complete the optional objective you'll also need a Living Heart artifact, that can be cooked or obtained in one of the following quests:
* Rescue "Duty" member
* Meet Kruglov
* Crazy Stalker's flash drive and/or Get a USB flash from a crazy sniper
=== Fistful and Chemist ===
Talk to Cross and give him 12x70 Buckshot ×30 Sidorovich gave you (he won't talk otherwise). He will direct you to an area in the eastern part of the forest where a shootout occurred. The area will be marked on your PDA map; look for the Wrenched artifact under a tree - as you approach it, Chemist and Fistful will spawn.
On top of a 3 rock formation, you'll find a critically wounded Fistful over Chemist's corpse below. Heal Fistful and exhaust his dialogue - he'll take some time over his friend's body and then walk towards Cross' camp. If you have a Living Heart with you, Chemist can also be revived by putting the artifact inside his inventory. He will follow you until you lead him to Cross' campfire. 
Make sure to escort both stalkers to the campfire and verify they didn't stuck inside some rock, otherwise they might disappear or won't be able to talk later. Selling them a broken shotgun with one magazine worth of ammo helps, as well as wiping the route out before healing/resurrecting.
From the stalkers, you will find out that they were ambushed and robbed by a group of bandits led by Baboon who is known to be handling Hog's dirty business. The bandits went to the Dump and are probably on their way to Dark Valley, so after escorting Fistful and Chemist to Cross you need to move fast to not lose them.
=== Inferno ===
When you walk to the Dump, there will be a large group of bandits heading northwards from the Forgotten Forest, toward the Dark Valley transition. Baboon is conspicuously the only one without a helmet, and is also the one carrying the Inferno artifact. You can try chasing the group from the back, or flank them and climb the [ unfinished construction site] as a vantage point for sniping.
After taking him out and grabbing the artifact from his body, you're technically done, but the rest of the bandits will halt their pathing and remain to cause trouble later if you leave them alive.
All that's left to do at this point is to deliver the ~4kg artifact to Sidorovich.
== Notes ==
* Talking to Fistful temporarily disables the transitions into Dark Valley until you complete the quest.
* Reviving Chemist with a Living Heart artifact is a wise thing to do, as his chain quest has fairly valuable artifacts. Chemist is also a key NPC for certain achievements, if you're a completionist.
* Chemist's body is set to not decay. You can revive him any time later, he won't rot away into a zombie.
* After completing this quest, Chemist and Fistful will sit by Cross at his campfire and will be some helpful added firepower if you want to pull annoying mutants and save ammo (especially for flies). You can sell them a shotgun with a magazine worth of ammo to make them more effective at that.
* Chemist won't talk immediately after coming to the campfire, give him a day to rest.
* Chemist and Fistful are protagonists of the eponymous STALKER fan fiction series, most known for assembling a working armored vehicle from an abandoned Mi-24 helicopter.
== Bugs ==
* Both stalkers might get stuck in the rocks or get lost on their way to the campfire, and there may not be any way to free them or get them back. Escort them manually and ensure that it doesn't happen. Fistful holds an item required for the The Secret Weapon of the Monolith questline, so he's especially troublesome.