On your second trip to Hengsha, there will be opportunities to do two different side quests to raise some credits for last minute Praxis Kits and ammo. These are actually best done together due to the close proximity of their objectives. I'll cover a fairly optimal path for completing both.
You can pick this one up fairly easily. After you walk for a bit through Hengsha, you should get interrupted by a terrible feedback episode on your augmentations. Once you recover and walk a short ways, Pritchard should call and explain the current recall. This will direct you toward the Hengsha LIMB clinic.
Stick to the low road from the construction site to avoid most of the Belltower guards in the area. There will probably be one at the clinic though, so approach carefully with a silent weapon or tranquilizer ready. You'll want to take him out before he opens fire on you. The civilians in line for the clinic will probably panic, but nothing much should come of it.
Go into the LIMB Clinic and talk to the doctor on the left to receive the recall information. I strongly suggest that you turn down the upgraded chip. It will only make things harder in the future, so put up with the temporary feedback issues for now.
Once you make your choice and tick it off the objective list, look to the left of the desk to find a Dr. Wing calling out to you. Talk to him and agree to help to ultimately learn that a heavily augmented mercenary apparently went rogue. He wants you to quietly track him down and bring him back to his senses, if possible.
The lead for this is a butcher shop in another district. Just take the nearby subway and you should arrive near the marker. Hack the gate or climb onto the rooftops to reach the back alley butcher shop. If you go through it and reach the office in back, you'll find that the rogue agents already cleared out after killing one of their own.
Search his body to learn that he was a Belltower mole. You can hack into the safe too, if you wish. The only lead we have on them for now is that they went into the sewer, which isn't much. It's not nothing though.
At some point during this, you should have gotten a message from Hugh Darrow about meeting a contact of his. Let's focus on that for now.
You can find Hugh Darrow's agent, Mengyao, on top of one of the buildings near Hengsha Courts. You should be familiar with these rooftops by now. Regardless, walk up to her and accept the contract get five individuals marked on your map. It seems that these terrorists have a data chip, and we need to not only get it back, but keep things non-lethal.
Walk over to the area near Alice Gardens, but be very careful. There are a number of Belltower guards near the entrance, so you can't get too close. Use a stun gun or tranquilizer on the single guard on the bridge, and then cross over it.
It's going to be hard to quietly take out the thugs from up here (unless you want to use Icarus to jump over and stun them, which isn't a bad way to start off the engagement), so move toward them until you see a staircase on the left. You can take this down to get on the terrorists' level.
Start by doing a quick quiet takedown on the man in the alley. You can then pull out a tranquilizer or stun gun and shoot the other patrolling guard near the exit of the alley. The two men standing together should just face the fire and ignore you as you quietly knock out their third patrol to the right of the alley. And with that done, you can just sneak up and either do a double takedown, or a takedown and stun gun combo to finish things up.
Grab the data chip off the marked man. It's not time to go back yet. This is where the quests cross.
Finding Zelazny in the Sewers
If you look at the ground near our little battlefield, you should see a manhole cover. Pull it up and go down into the sewers, then move forward to spot a group of four men sitting in the back. It's time to wrap up Talion A.D.
Note that if you plan to fight them, don't try to talk to them, just start with a dual takedown and go from there. It will be difficult, but far from impossible. Just jam the takedown key and try to run for cover in the tunnels if you plan to use guns.
There are a few conversation paths available. You should be able to reason with them with the help of pheromones. The one important note is that you're really free to choose whatever you wish. If you want them to turn themselves in, that's fine. You can also agree with their cause. It just changes the ending of the quest. The only material difference is that letting Zelazny will earn you a favor with his old Belltower friends. They'll move some patrols out of the streets to make a few spots less annoying.
Dr. Wing will only give you the reward if he feels that you did the right thing. Reasoning with or killing the men should net you a Praxis Kit. If you let them go, you can either lie to him, or tell him the truth and use the convince option and the “maybe you're not so different" argument to at least get him to see your point. If you do this, he'll understand and hand over the Praxis Kit.
That will close things up for now.
With that done, take the trip over to see Mengyao again. Before you hand over the chip, you should try to at least find out what's on it. If you inquire, she'll shut you down. If you have the social module, you can persuade her by using the “Charm" option. Note that this will also secure you the “Ladies Man" achievement and give you a little backstory on what's going on at Darrow's project.
Doing this should set you up with a lot of money and potential augmentations, so upgrade as you chose and then continue with the main quest.
- All information and screenshots from Deus Ex: Human Revolution.