Enemy within

Somebody from Freedom stole Lukash's Zastava M91, a one-off modification of Zastava M76, along with some other items. He wants you to retreive it and the PDA from the thief as well. The gun had a GPS beacon on it, and the thief is currently in the Bar; you have to hurry up before he disappears.
Stages of this quest are unmarked.
== Walkthrough ==
=== Pursuit ===
Go to the bar and ask Garik about a guy with a Zastava. Garik tells you he went to the Dump, and he's already changed his disguise to stalker's. He also managed to steal some items from Duty.
Head over to Dump, and ask Prapor about the thief. He asks you to help defend the checkpoint from the incoming mutant wave, and a pack of pseudodogs attacks it immediately. There are three waves total, with the next being dogs and pseudodogs, and boars and scorpionflies. After defending the checkpoint, Lukash messages you again, saying that the GPS beacon signal has been lost in Agroprom.
Travel to Agroprom. At the entrance from the Dump you will be ambushed by bandits from all sides. Go to Adrenaline and ask him about the thief. Turns out the thief stole some weapon addons from Adrenaline as well.
Marked One broadcasts a message into the general network about the thief, and gives his supposed profile. Some stalker contacts you and confirms that he saw the thief heading towards Central Pripyat.
Move to Central Pripyat, and speak to Doctor. Doctor says that the guy has been wounded, and can be found in a room near him. The stalker's name is Tick. Speak to him, and give him a First aid kit to heal him. The stalker will act confused, saying he doesn't have a uniquely modified rifle, just an ordinary Zastava, and apparently Marked One took him for someone else. However, he tells you that some guy gave him this suit, and told him to travel to Pripyat. In exchange, he gave the guy a black trenchcoat, and went to the [ quarry at Jupiter].
=== The thief ===
Head towards Jupiter and visit the quarry. You are unable to find the thief there, but after exploring the cabin of the giant excavator, you can found that it's mined. Detonate the mines and enter. Inside, you can find the backpack with the goods that look suspiciously like the description of the goods stolen from stalkers previously.
After picking the stash up, a group of 11 bandits spawn around you, lead by Chameleon. Kill them and search Chameleon's body. You will find the broken Zastava M91 he stole from Lukash, and his PDA as well.
=== Finishing the quest ===
Return the rifle (no need to repair it) and thief's PDA to Lukash. He will promise to let the Duty squad pass at night, advancing A short ceasefire.
== Notes ==
* The mutant assault on the Dump Duty checkpoint is the most dangerous part of the game for Prapor, Bullet, and Max Lyuber along with Demyan Ivanhoe and Sergey the Shaggy if they were saved earlier in the game. The mutant waves can easily kill them or lead to friendly fire deaths if you don't act quickly. Since the waves spawn around you, run as far away from the checkpoint as you can once the two dog waves have been dealt with and handle the third on your own.
* If you enter Agroprom from Yantar or Swamps, the bandit ambush might not appear until you touch the entrance from the Dump.
* The reward from Lukash is the blueprint for Zastava M91. You can make Vasily craft the weapon based on it.
== Bugs ==