Go left and enter the drain pipe to get into the water treatment plant. Follow the walkway until you come to a locked fence. You can climb the ledge to the left.
Keep moving. You'll enter a large room with a spiral walkway along the outside. Follow the walkway to the gap, then jump down. From there, jump up and hit Y to climb back up on the other side.
In the next room, you'll see a drone on patrol. When it turns around, quickly run up and kill it before it gets too far along. There are two other drones further into the room.
Locate the drones and use the dead one's gun to kill them. You shouldn't have too much trouble, but there's not much of a good way to sneak up on them because of the lights in the area.
Bounty! At the bottom of these few steps, turn left and go around to the other side of the railing. Back toward the top of the staircase is Bounty Card 15.
Just keep following the hallways. You'll soon come to a ladder. Climb up and you'll find another ladder, leading outside.
Turn left and drop down. Walk toward the door below, turn right and drop again. Then look to the right wall for a piece of metal you can climb onto. Use it to shimmy around the corner and climb across the cliff face.
At the other side, drop down and walk to the edge near a building. Drop down again onto the rocks below and follow the path to another place to shimmy along. Climb up at the end, then climb up to the walkway. Follow it to a crate, climb that up to another platform, and look up for a hang rail.
Take the hang rail to another walkway. That leads to ladder. Climb that to another walkway, and take it to a dead end. Turn right to see a pipe you can jump to. From there you'll find another ladder.
At the top, walk to the dead end and hit Y to climb up again. Shimmy left and you'll find a platform.
Bounty! Your reward for all this light platforming is Bounty Card 52, found where you climb up.
Hop on the crate and then jump over the fence to the platform below. Go through the door and hit the console.
The door behind you is now open. Go through and turn left. You'll see a merc-controlled drone heading up the stairs. Either drop on it or behind it for a stealth kill. Then proceed down.
Through the next door, turn left and take the ladder down. Walk through this area to a door back outside. Once there, turn right to watch a colonist get shot by a drone. Proceed on the walkway to the crate and climb up, then spin around and use the hang rail to get to where you just saw that murder.
Drop down and enter the drain pipe. When you exit it, look left for a crate. Use it to climb up to the next floor, then take the ladder there. You'll find a door to your right.
The path to the left will be closed off by an explosion, so go right to a door. Follow the walkway to where you can drop down to a wooden path. It collapses, alert the drone below slightly. Drop down to him and kill him, then turn left and take the path.
Drop again to take the tunnel leading back behind you. Keep moving through the tunnels and you'll soon reach ... more tunnels.
Just keep going. You'll hear mercs talking and find some bodies and a ladder. Go up and you'll see them move off into the compound. Quickly assassinate the one that stays behind, then move back toward the ladder and into darkness.
Climb up the second ladder in this room to get above the area. Look down from the center wooden plank after a few seconds and you'll probably find another drone. Drop on that one to kill it, then retreat back into the dark. Climb back up and look for a third drone down on the street to the right.
Either shoot with a drone gun or sneak up and melee this last fighter. That frees you up to explore much of the surrounding area.
Bounty! Follow the street to the right to a door that's marked Supply Depot. From there, turn left to see a small dead end. Walk to the end of it and look in the left wall for a small cubby hole, the home of Bounty Card 3.
Backtrack and go the way the first set of drones did. You'll go through an alley, at the end of which you'll find a drone. If you're careful, you can kill it without being seen. Otherwise, you can try to find a way there using the rooftops. If you come to a ladder near a drone banging on a door, go to the right to get above the drone mentioned above. Kill it, then go through the archway nearby to get behind the two drones trying to get at the survivors.
When they're all dead, approach the door for a cutscene and a new mission.