Deus ex human revolution tong rescue mission location?

so i just got the dlc that gives me the tong rescue mission and im trying to find it and all I have to ask is do i have to look for a guy or does it activate automatically?|||If you have it, Tong Si Hung will tell you to go save his boy the second time you meet him. In the Harvester hideout abandoned carpark. A section of the sewers will now be accessible.