There are 15 gang hideouts to discover in the Chicago area. Once you do so, you'll unlock the AK-47 on your weapon wheel, as well as the Spec Ops SMG-11, the option to upgrade your weapon reload speed from the Skill Tree, and an achievement trophy.
Hideouts are scattered throughout the area and can be cleared in any order, also earning you skill points in the process. Your goal is to perform a takedown movement on the gang leader, not kill him. I'll provide brief notes on each hideout below, sorted by area. If you don't see a hideout on your map, keep looking around; they come up naturally over time, as you profile random people in the street.
Brandon Docks: Gone in a Flash
Northwest of a hideout near the east side of the Brandon Docks region, you'll find a hideout. From the start of the mission, it's across some tracks and straight ahead. You can hack into a camera and look around the area to disable guards that might call for reinforcements, assuming you've learned that ability. There should be two or three of them, and there is also a marksman who likes to stand on some crates and take shots. You can safely approach from one end of the complex and work your way slowly across, toward the marksman. Along the way, you'll likely scare out your target and he'll make a run for it. Hopefully, by then you've mostly cleared out the gang members and you can simply chase after him and use a takedown move. Then you can either leave or finish defeating goons.
Brandon Docks: Packing
Not far from the south side of the Brandon Docks region, near a newspaper stand, you'll find the start of another search for a gang hideout. Accept the mission and head across the bridge, to the area on the far side. You can find a fence on the approach. Use it for cover and get close, then look right to find a camera. Hack into that camera, and look for more of them that you can use to survey the area and disable any phones that can be used to call for reinforcements. You can also have a few units self-destruct with their explosives, though watch that they don't manage to throw their live grenades and kill your target (that happened to me once). Remember: you need him alive. The target is inside, on an upper ledge. He's difficult to reach there, and may run to a waiting truck if you get close without knocking him down, so be ready to pursue him in another vehicle if need be.
Brandon Docks: Port Authority
A short distance southeast from the hideout in that portion of the Brandon Docks region, you'll find the start of the next gang hideout raid. Head up the street to the shipyard. You can enter from the side and work your way across, starting near the blue locomotive. Make sure that you disable reinforcements, as you'll otherwise have to deal with cars full of goons. The best way to do that is to circle around the building riding cameras. The first camera is on a pole right near the locomotive. As for your target, he tends to hang around on a balcony in the upper level of the warehouse, though he'll possibly go out and explore once the shooting starts.
The Loop: No Parking
Northeast from the Bunker area in The Loop, there's a gang hideout. The gang's area is a short distance north. You can ride a lift up the side of a building to an opening, then jump behind a low wall and use cameras from there to survey the area. If you prefer, you can instead head up along the ramps cars use to reach the second and third floors. Either approach is dangerous, because the thugs are on multiple levels, and ascending the stairs between levels while they are on high alert is a tricky affair. The target is on the building's third floor, near one edge. The most effective approach is to start by using cameras to get views that allow you to disable phones that can call for reinforcements. Then use takedown moves to stealthily eliminate everyone on the second floor. From there, head up to the third floor by way of the ramp, then make your way across that floor to reach the leader and knock him down before he gets spooked and flees in a vehicle. If you start shooting on the second floor, a civilian in the streets below will call the police and they'll make everything more difficult, so try to avoid that (in my experience, the police aren't called in if the thugs are the only ones shooting on that level, however).
The Loop: Street Cleaning
Right along the north central portion of The Loop, south of a bridge connecting that region to Mad Mile, you'll find a street corner opposite a series of skyscrapers. There is an alleyway behind them, with a marksman on a high ledge and your target on the lower ledge, out in the open. From where you first appear, head around the building toward the left. Approach along an alleyway with a large dumpster. From there, you can take out a nearby guard, then lower the forklift's load of bags of cement. Climb onto that load and then to the ledge overhead and take out the marksman. That will make the rest of your raid go much more smoothly. Descend the way you came, and continue down along the staircase near the forklift. Take out guards one at a time, until you have knocked down your target in the open space near the base of the towers.
The Loop: Two For One
Close to the far west side of The Loop region, a hideout mission awaits on a street corner. Across the street, to the south, you'll find the hideout. There are two fantastic approaches. You can sneak around back and ascend some stairs, then quietly take out the guards, or you can run forward from where the mission begins and climb up some ledges to a rooftop.
I recommend starting there and using takedown moves to eliminate the guys on that nearest rooftop. Disable any of their phones, as well, by hopping around rooftop segments. Then descend the building and work your way around to the back staircase. You don't want to make noise during your raid because the police will be called to the scene if you do (after all, this all plays out right in the middle of a city block, over a plaza full of people). From the top of the referenced stairs, one target is on a lower balcony ahead, toward the rooftop area with the solar panel. The other is on a balcony ahead and to the left, below the high ground where you can take out a marksman as he stands near an explosive panel on the wall. Profile the two men, then quietly knock them down and either escape the area or rid it of any remaining threat.
Mad Mile: The Low Road
Near the north side of the Mad Mile region, you'll find a plaza area near some elevated train tracks. Accept the mission and head northwest, to the area indicated on the mini-map. It is an underpass area. You can head around to the left side and sneak in there, taking out guards as you advance across the area toward your target. There are a few other entrances, as well, so you might want to sneak along multiple entrances, getting rid of guards near the outskirts of the area and working inward. There are three soldiers who can call in reinforcements, so eliminate them before you get too ambitious. If you are spotted, your target is especially likely to run, so be ready to give chase if he gets in a vehicle and tries to leave.
Mad Mile: The Tower
Along the south central portion of Mad Mile, you'll find this hideout to invade. From the starting point, it's located straight up an alleyway and across a street. You can approach from the front. There's a lift near the base. Hop into it and hack the lift to rise up to an overhead level. Then continue toward the right, using concrete columns as cover as you wind your way up and around the tower. You don't have to worry about being spotted until you receive a notice that you are entering a restricted area. The first guard is just ahead of a fence. You can duck behind paletts and look on a post ahead to find your first camera. Then just proceed as normal. Partway up, there's a lift you can use if you want to stealthily arrive on the upper level where your foe is waiting, though that won't work if anyone has already been alerted to your presence. This is a fairly standard operation, as long as you remember to watch out for guys on the upper level who can fire down at you as you ascend. Don't let them use that fact to catch you by surprise and you'll do just fine.
Parker Square: Union Dues
In the Parker Square region, a short distance northeast from the hideout, you can find another hideout to raid. It's south from the starting point, almost directly due east from your hideout. Enter from the scaffolding along the street. You can see a camera ahead and use that to travel around the building, taking care of reinforcements if you have the ability. There are three buildings joined by construction: the one where you're located, one across a wide alley and one to the right that serves as the link. You can start with the two thugs nearby, then descend some stairs and start along the one to your right, which is where you will likely find your target. Eliminate him and then either escape or finish the job to clear the raid.
Along the south central side of the Pawnee area, you'll find a shack near a sign pointing toward a beach. Just down that road is the target area. You can head down a dirt road that branches off from the paved one. There are three targets here, so take things slowly. You can probably take out the guy along the road without much trouble and without being seen. Then head back around and left to the guy on the docks, close to that road. The third guy patrols the area near the far docks, and he's harder to reach without being detected because the guards are so close together. You may need to run and gun at that point. It's all very doable, though.
Pawnee: Burning Bridges
Travel to Pawney's motel and you'll find the starting point for your raid. The hideout itself is at the other end of the nearby traffic tunnel. There are three targets for this raid. You can head down to the water and you'll find three high towers that you must navigate, often with poor cover from enemies it is easy not to even notice, which makes this one of the most involved raids out of the lot.
Climb onto the closest dock and take out a guard there, then climb the steps nearby while keeping to cover, so that you reach the top of the first tower. Watch for a guard near the top. You'll have to cross over the catwalk bridge from there, to the next tower. Descend in an elevator and you will find a target patrolling at the base. Eliminate him without being seen by guards on a higher ledge extending from the tower to the right, across some water.
There is a low, gray wall in this area. Hide behind it and interact with the Crane to glide out over toward the distant tower. There, you can take out some guards, including a second target. As you ascend, you'll find yourself at the top of a bridge. There is a marksman in a distant tower. Snipe him, then run forward along the bridge and you should be able to spot your target. He likes to stay out in the open, so make sure you don't shoot him by accident. You can descend to the water and then swim over to the third tower, then ascend along the stairs to reach the target. Take him down and the raid is done, provided you escape any remaining threats.
Not far from the northeast area of Pawnee, a short distance northwest from the north side of the broken bridge, you'll find another gang hideout activity. The actual hideout is a short distance west, across the street. This is an easy hideout to begin invading. You can head left up a hill and take out a marksman, then drop down and take out a couple of guards near the gate entrance. Then you can hack into a camera near where you eliminated the sniper and safely use that to soften up the troops before you drop down along the bank and work your way around the outer area, slowly picking off guards one at a time before moving inward with the tombstones as cover so you can get close enough to your target to knock him down.
Pawnee: Out of the Woodwork
Look along the west side of Pawnee to find a gang hideout. It is located across a bridge, closer to the southwest corner of Pawnee. You can head near it and crawl along the fence to reach an opening, from which it's easy to scan a camera on a pole. The camera lets you soften up the enemies and disable their ability to call in for support. As you mess around and take out the first target, a second one will head for the area. You have some time, so hopefully you can take out all of the current crew and then run up the hill to the area where you first entered. Hide by the fence there and wait for the new arrivals (including your second target) to slowly walk around and investigate. Take out your target and his friend, then run away as fast as you can. With any luck, you'll escape the area without having to battle any others.
The Wards: Compliments for the Cook
Toward the west side of The Wards, east of the dam's south side and only a short distance northeast from your hideout in the same vicinity, you'll find another gang hideout to raid. From the field where you accept the assignment, travel east. You can hide near a dumpster at the entrance area, then hack into a camera and do your usual damage to the crew before you follow through with your effort to find and knock down the leader. Note that it's possible the shooting will cause someone to call the police, so it's best if you can take everyone down quietly and not have to deal with that threat. Otherwise, the mission won't end until you ditch the fuzz.
The Wards: Swap Meet
Right near the southeastern edge of The Wards, not terribly far from the western hideout in the Brandon Docks area, you'll find a gang hideout. A short distance northwest from where the assignment begins, there is a yard below the train tracks. The man you're after roams around right near the front. If you're lucky, it's actually possible to draw him right to the gate by triggering an explosive on a closer guard, then take him down and run off the property before his friends have a chance to make your life difficult. Otherwise, use hacking to weaken your resistance and then go in the old-fashioned way.