Friend from K-Bar, Iliana, calls you and ask for help about her kidnapped friend. Before you get there, inform the officer Teng about this case.
After getting to the bar talk with the russian girl. She'll tell you that Katuschka had a sponsor, Mr. Chan. He sits on the couch nearby.
Convince him to give you the girl's address and go there, leaving bar through the backs.
Check the phone in the apartment and photograph a note hanging on the fridge. It'll be a phone number which Teng should check.
Call Teng and the mission ends.