Searching for Proof

M1 - Searching for Proof is a main mission in Deus Ex: Human Revolution.

Primary objectives
Enter TYM's Tower by passing through the Pangu.

The TYM employee shuttle lets you out into an empty shuttle station. Search the surrounding area for loot. Go through the available exit and up the stairs. On your way up, there is an explosion. Reaching the next level triggers a cut scene in which a TYM employee begs you to save him from toxic gas (which was released in the earlier explosion). Helping him is optional. See secondary objectives for more details. Proceed on to a machine control area with a guard and two technicians. You can bribe the guard for 500. If you helped the employee you encountered earlier, that will provide a way to get past the guard for free. Intimidating the guard will fail and lead to a fight. Bluff will allow you to gain limited access to the area with the guard attacking you if you get too far away.

The control area overlooks a manufacturing plant. Your first goal is to get to the elevator on the far side. There are two ways through. Regardless of which method you choose, once through the plant and have taken the first elevator, the last part of the path to the second elevator has one more guard and a final room containing an electrified floor and a series of boxes leading up to a ledge. The switch for the electrified floor is in a caged off area that can be reached by hacking the lock. Alternatively, if you go into the room with the electrified floor (only part of the floor is affected), you will find a vent on the right side of that room. The vent leads back into the caged area. Once the electricity is turned off, climb the boxes to the ledge, follow the ledge to a ladder, then climb the ladder up to the final room which contains the elevator. There is additional loot in this room. To the right of the elevator is a space closed off by a crate. Move the crate to gain access. To the left of the elevator is a vent. Following the vent will drop you into a space with a dead scientist and a special eBook. You must have the Icarus augment to reach this particular area.
 * Take the stairs to the right of the control area down to the plant floor. From here, move around a series of cameras, guards, and laser sensors to reach the elevator.
 * Back in the control area, hack the level two device on the panel overlooking the plant. This unlocks a button that re-positions the catwalk. This lets you bypass security by going to the room in the left and climbing up the ladder. This leads to a vent and a tunnel that drops down, but you will need the Icarus Landing Augmentation to proceed this way.

Find and view van Bruggen's Recording
Once you take the elevator, it lets you off into a large lab center. Pritchard informs you that the area is safe but that you should conceal any weapons. The initial part of the lab center has several employees who will ignore you and three guards who are friendly as long as you stay out of any locked rooms. Your goal is the lab behind a set of guarded doors. You can access this area in four ways. Once in, continue through the lab and up another set of stairs. You'll notice a large door staight ahead guarded by a security camera. First, turn left and head through the door at the far end of the catwalk. There is Praxis Kit in the  desk drawer in Laboratory B-2. Explore the area if you wish, then head back and through the large door mentioned earlier. Go down the hallway and up the stairs. Look for the data core signs and head right to the front of data core room. You can gain access to this room in several ways. The data core room is guarded by numerous laser sensors. Your goal is to get through it and to the elevator at the far end. Simple observation reveals the correct path through the lasers. The Cloaking System also makes this incredibly easy. There are also guards in a nearby security room but unless you trigger an alarm, they will not see you. It is also simple to take out the guards. To do this, about halfway through the data core room, you will see a server space protected by more laser sensors. The bottom laser flickers on and off, making it possible to sneak past. In that room is a crate. Moving the crate reveals a vent. Follow this vent around and into the security room with three guards. The room also contains a dedicated terminal and a security hub that, if hacked, allows you to shut down the lasers and the camera above the elevator, respectively.
 * Take out the guards and hack the doors to the lab. The doors are in view of a camera.
 * Sneak through rooms to the right of the lab entrance. This requires more hacking.
 * Secure a pass into the lab. Near the lab entrance is a security room that can be entered either by hacking the door (this requires taking out the nearby guard) or sneaking through a ventilation shaft accessible in a neighboring room. In the security room is a pass. Taking this pass and presenting it to the guard in front of the lab entrance will give you access. This is by far the easiest method as no other guards will bother you until you reach floor with the data core room. If you listen carefully, on your way to the lab you can overhear a TYM employee complaining about having trouble getting a replacement for his lost pass.
 * At the far end of the lab area is a balcony with an open railing. You can jump up to this balcony by moving the vending machine located nearby.
 * If you have the CASIE augment, you can sweet talk your way past the first guard you meet and into the server.
 * Sneak past the guards. If you have the Glass-Shield Cloaking System, you can sneak past the laser grids. The grid to the far right of the main entrance can also be hacked. From there, you can choose a variety of ways to enter the data core room, including hacking doors or security hubs.
 * As always, it is also possible to simply shoot your way in.

Take the elevator up. Getting off the elevator triggers a cut scene in which you discover the information stashed by van Bruggen.

Find Zhao Yun Ru
After the cut scene, your next goal is to find and confront TYM CEO Zhao Yun Ru. Move down a hallway guarded by laser sensors which are very easy to avoid. The next hallway has two offices which can be explored. Following that is an office space with two guards. The security hub to the camera watching the room is in an office on the right side of the office space.

Once through this room, proceed through more hallways. There is a security office with two guards who you can either take out or avoid. If Narhari Kahn is still alive, he will also be in his office. Otherwise, his office is empty. The final office is guarded by a security camera. There are two ways through. Either method gets you to an elevator that takes you up to Zhao's office. If you saved Arie van Bruggen's life by giving a weapon during the mission Gaining Access to Tai Yong Medical, he will contact you while you're on the elevator. He will thank you by hacking your bank account...and giving you 2000 credits.
 * Hack the door on the left side of the room. It is possible to find a code. The security camera will spot you, so be quick. If you have an EMP grenade, you can permanently disable the camera.
 * Move to the room through the door underneath the camera. Back there is a weakened wall which can be broken out.

Rescue a TYM employee
If you decide to help the TYM employee trapped by the explosion, there are two ways in. Once in, use the nearby valve to shut off the gas. Then reach the employee by moving the crates and crouching. The employee thanks you and tells you to mention the name Lee to the guard ahead. This lets you get past the guard without having to bribe or persuade him.
 * The first door you encounter requires a level 3 lock hack (there is a pocket secretary with the passcode for the door at the end of the hall on a yellow trolley).
 * Going round the back brings you to a level 1 lock hack but the room you enter is filled with gas so you must have the Implanted Rebreather.

Talking to the trapped employee and subsequently cashing in the favor with the guard does not invalidate the potential ghost bonus.