Deus Ex: Human Revolution/Securing Sarif's Manufacturing Plant

Head through the door by the two police officers, and take the hallway around to another door by a group of cops. When you're out of the roof, Pritchard will talk to you over your InfoLink and tip you off to a possible rooftop point of entry into the plant. Take the ladders down to the lowest level and you'll encounter the first bad guy around the corner of the building.

Enter the building
There are plenty of ways inside the building. You can start a shootout, shoot or throw the red explosive barrels, or try moving from cover to cover and taking guys out with whatever weapon you got from Sarif in the helicopter. For the sneaky way, and the course that will get you the Ghost bonus the easiest, you can use the box on the forklift next to the first guard to get up onto the shipping containers and make your way to the roof. Before you go up, there is some Stun Gun ammo in the little room next the forklift. Above the shipping container, take the ladder up to the top, then enter the fenced off area and move the box aside to reveal a tunnel behind the machines. On the other side you can turn off the electricity at the power shutoff and keep going through the fences around to a vent that will let you into the building.

Get to the first locked door
Inside the plant, you'll get an updated location marker, which is an elevator that will take you down to the Factoring Labs. First you have to get to the north end of the first floor. You start out in a large warehouse with some patrolling and stationary guards on the ground floor. On the west side is where you enter if you came in through the roof, and on the right is a higher level with some tranquilizer darts and a vent that will let you bypass the rooms beyond and go straight to the other side of the first floor. The vents above also let you drop down in various places in these rooms, if you're keen on taking out bad guys or looting lockers.

On the ground, you can sneak from cover to cover on either side of the warehouse to make it to the doors on the north side, which will take you into some hallways and rooms. In the west room are two terrorists messing around with a turret, and in the hallways in the center are three guards who will split up to patrol the two other rooms and far hallway after having a brief conversation. If you're not looking to kill or knock out everyone, the upper vents are the way to go. You can also find some ammo in the lockers in the southwest room where you come down from the roof, and some credits, ammo and a concussion grenade in the locker room, which is the northernmost room before getting to the end.

When you get to the end of the hallway, Pritchard will inform you he can't open the Assembly Room door, so you'll have to hack it. You'll also get the hacking tutorial if you need it. It's a simple hack, just capture the directory on the left and go straight to the registry from there. Beyond the door you'll be decontaminated before being let into the next area.

Get to the elevator
Beyond the security door lies an open lab, with camera-surveilled hallways in the southeast that lead to another lab, on the east side of which you'll find the elevator. You'll be up on a low mezzanine looking down on the first lab where one terrorist is patrolling near you and three others are gathered around a dead scientist they're discussing. Across the lab from you, on the far mezzanine is a room containing the hostages, your secondary objective. If you have the tranquilizer rifle, you can start knocking guys out in relative safety, while an attack with lethal weapons can be initiated at any time. It's somewhat dangerous to try traversing the lab floor using cover, since there are four of them and they have varied patrols, but a vent behind a crate below the eastern stairwell will give you access to an upper route. It also lets you into the hostage area without tripping the alarm that sets off the gas bomb inside. There is also a storage room in the northwest corner of the lab with another terrorist who will come out to support his friends if you cause a commotion.

If you enter the hostage area through one of the doors, it will trigger the detonation sequence of the bomb on the desk in the middle of the room. You will have 30 seconds to hack the device to shut it off. If you come in through the vent, you'll still have to deactivate it, but you can take your time. One of the guards out in the lab has a pocket secretary with the code on it as well. When you have the bomb disarmed, you can talk to Greg Thorpe, who will tell you his wife is missing somewhere in the factory. When you've finished up in the lab, head into the hallways, either through the east entrance by the hostages or the south entrance by where you first came in.

Inside the hallways where the alarm is sounding, you'll see they're covered by cameras and a roving guard, and you'll get the security systems tutorial. Just watch the cameras and move when you see they're facing away from you. You'll also want to stay out of the guards sightline, unless you're prepared to start a fight. As you make your way down to the southern hallway, you'll pass by a meeting room that has two more terrorists in it. If you're avoiding conflict, get close to the south door until their conversation ends, after which they will move into separate corners and you can enter without being spotted. The guards have a few credits on them, but otherwise there's really no reason not to skip the room altogether. Down at the end of the southern hallway, you'll have to hack another door, which leads into the next lab.

This lab is a lot like the first one, except it has two storage rooms, at the north and south ends. The northern storage room can be accessed by vent, but there's no vent route to get you across the main lab this time. If you're not going to fight everyone, the easiest way to sneak across is to use the cover along the southern wall. Once you get to the east side, use the elevator to get down to where the Typhoon is.

Find the Typhoon
When you exit the elevator, grab the Praxis kit in the middle of the hallway and check out the Augmentations tutorial if you need it. There's nothing critical you need upgraded at this point, so don't feel bad about saving it for later. Around the corner, the hallway leads to an intersection covered by a camera and a turret. On the other side of the intersection is the security room, where you can turn off the camera (and the turret, if you used your Praxis kit on the Turret Domination upgrade to your Hacking: Capture). Instead of crossing the intersection, you can also use the vent behind the crate in the west wall of the beginning of the hallway to cross over behind the turret. From there you can just move on through the door, or drop boxes in front of the turret so it can't see you, allowing you to more easily sneak around down the hall. Inside the security room, you'll find two computer virii and a pocket secretary that has the code to the security computer.

Whether you bothered with the security room or not, head through the door behind the turret to find a hacker inside the inner room. When you approach him however, he won't let himself be captured alive. You'll get the Typhoon Augmentation Prototype and talk to you boss through the InfoLink, and he'll give you your next objective.