. >> reporter: el vin hernandez is an investigator for the department of homeland security, which coordinatesnternational anti-sex operations. he's helped rescue dozens of women from neighborhoods just like this one. this is a house? >> yes, this is a house right here. it's right across the street from a public school. they can house themselves anywhere. if you're not aware of how traffickers operate, you're not going to think anything is wrong. it's just the normal course of the day. >> reporter: what do you see on a regular day here? >> on a regular day, these streets would be full. guys would be hanging out on corners, handing out cards to find clients to bring to the brothel houses. >> this is basically the length of walking i'm going to be doing. >> reporter: we want to see inside the u.s. operation. so we send our colleague out into the busiest part of queens, new york, with a hidden camera, to see if we can get an extremely rare look into a working brothel. >> i'll try to have a long conversation, all right? >> yeah. >> do you see him? okay, so they went around the corner. they're goin