Find Ahti, the janitor
When you're finished speaking to Emily Pope, she'll mention being able to hear someone singing. Leave the boardroom and go down the corridor opposite, towards the elevator. Interact with the button and head toward the Maintenance Sector to meet the janitor again.
Leave the elevator and run forward toward the NSC Control Room. Keep going forward, round the glass with the floating Hiss Guards inside, until you reach an area with some more enemies. Kill them all and you'll be able to cleanse another Control Point.
Go through the next door and more Hiss Guards will spawn. Eliminate them all and go through the door at the far side to reach the Janitor's Office. You'll be able to hear Ahti singing to himself, so interact with the door which has a poster on to find him in the next room.
Find a way to fix the NSC Power Plant
During the cutscene, Ahti gives you Clearance Level 2 so you can now access more areas. There's also the first side mission available on the noticeboard, called What A Mess: Burn The Trash, but since you don't need to complete it for the main story, we're skipping it for now.
Leave Ahti's office and go up the stairs, towards the red glow. Keep following the path then stand in the elevator when it arrives and descend to the bottom, then when you emerge there'll be some friendly security guards around the power plant. Enter the first door on the right to find Chief Arish, head of security for the FBC.
Fix the NSC Coolant Pumps
When you're done talking to Arish, head up the stairs to claim another control point. You've now got two objectives to tackle; head left at the base of the power plant to go to the Coolant Pumps. Kill all of the Hiss Charged – new enemies that explode when near you - and head through the next door, following the signs to the Coolant Pumps.
There'll be a few more enemies to kill in the next room, then you can cleanse another Control Point. Follow the next sign to the pumps and you'll drop into a rocky area with a few Hiss Guards along the way. Eventually, you'll reach the NSC Coolant Pumps.
What you need to do here is use the Launch ability to pick up the cubic power sources and insert them into the available slots on the sides of the blue machines. There's three in total, but the one at the far end of the room will have something blocking it. Shoot the enormous disgusting tentacle things to clear the path, then make your way through the pipes, shooting all of them as you go. When you've cleared them all, re-insert the power source to fix the NSC Coolant Pumps.
Trooper Second Class Coppack boss fight
Of course, now a boss spawns, and this one has a minigun. Trooper Second Class Coppack isn't too tough, you just need to make sure you stay in cover whenever he;s firing his minigun, and use Launch to take down his shield. Headshots do much more damage so try and hit as many as you can, along with throwing objects whenever your gun is reloading. Eventually you'll take him down, then travel back by taking the elevator ol' Coppack arrived in.
When you return to the power plant, enemies will have stormed the place while there's just one or two guards firing back. Help them out by clearing the swarm of Hiss, then start making your way towards the NSC Energy Converters. There'll be plenty of enemies to take out on the other side of the power plant, so kill all those then go through the double doors.
Fix the NSC Energy Converters
This is a fairly linear path, so head through and kill all the enemies you come across. When you've cleared the area around the energy converters themselves, grab another power supply and start filling in the available sockets. Again, there's three in total, then when you've done the third one, the Control Room will open up and you'll be able to lift the lockdown.
Go through the double doors on the top level and you'll go into the room you walked past a while ago, which was blocked off by glass. Kill all the enemies then cleanse the Control Point to lift the internal lockdown. Afterwards, interact with the huge machine in front of you and Jesse will insert her pistol into a mechanism and open the other sectors. Use the fast travel to head back to Central Executive and reveal the reason you're really there to Emily.
A Merry Chase (Evade ability)
When you pick up the side mission called A Merry Chase during this chapter, you don't have to complete it right away. When you do tackle it however, completing it rewards you with the Evade ability.
Head to the Janitor's Office in maintenance, then go down the long corridor toward the break room with the flashing red light. A few steps in and Jesse will fall through a pit, taking you to another alternate dimension. Complete this section to unlock Evade and Air-Evade.
A Good Defense (Shield ability)
There's also the side mission to unlock the Control Shield ability called A Good Defense. Go to Central Maintenance and follow the signs for the Training Course, although you'll need to shoot a few red pulsing blobs to be allowed access.
When you get through to the Field Training Course, all you need to do is complete the course in the required time. All you need to do is shoot a few targets and use Launch to place power blocks in the right sockets, but it's harder than it looks. I'd recommend combining Launch with your pistol to hit the targets, and when you need to pick up a power block, make sure you've got one targeted because waiting for your energy to restore can waste a lot of time.
When you make it through the door at the end, Launch some debris at the safe to bring down the shield and interact with it, then complete the tutorial. Survive the onslaught of enemies at the end and voila, another Object of Power complete.
Main Missions:
Control walkthrough: Welcome to the Oldest House
Control walkthrough: Unknown Caller
Control walkthrough: Directorial Override
Control walkthrough: Old Boys' Club
Control walkthrough: Threshold
Control walkthrough: My Brother's Keeper
Control walkthrough: The Face of the Enemy
Control walkthrough: Finnish Tango
Control walkthrough: Polaris
Control walkthrough: Take Control
Side Missions:
Control walkthrough: Old Friends
Control walkthrough: Fridge Duty
Control walkthrough: Self-Reflection
Control walkthrough: Mr Tommasi
Control walkthrough: Old Growth
Control walkthrough: A Matter of Time
Control walkthrough: Langston's Runaways
Control walkthrough: The Enemy Within
Control walkthrough: Mold Removal
Control walkthrough: What a Mess (all missions)
