Distance covered: 34,119 km (21,201 miles)
Subjects found: 74
At last, Moreno and I have the name of M's village. Today we went on a reconnaissance mission to the town nearest the village, with an outside hope of arranging a meeting.
The town centres around a thick strip of asphalt lined with ugly, squat buildings, like beasts crouched shoulder to shoulder on the banks of a dirty river. The land is flat, the heat oppressive, the traffic relentless - there is nothing here to recall the cool, clean air of M's home in the mountains of Vietnam.
Last night, I spent more than 90 minutes on the phone with M and P, discussing the possibility of their return to Vietnam. Whatever the girls choose to do, they will do together. For the first time, they seem to be gathering the courage to break with their lives here in China.
The biggest emotional challenge for them both will be leaving their children, who are legally Chinese and almost certainly can't be taken back to Vietnam. It's an agonising choice for them, and a terrible price to reclaim their freedom.
But there are other concerns, too, some of them quite surprising for girls so young.
The girls worry that they have lost their chances for love, and that they will be left outside their former social spheres. Listening to them speak, I began to understand the emotional toll that three years of isolation from their families and friends have taken.
I want these girls to know that they are not alone, no matter what they've been through. Many of you have asked what you can do to support The Human, Earth Project in a non-financial sense, and I have an answer for you.
If you know M or P personally - or even if you don't - please take a minute to tell them how you feel. Record a short audio message on your computer, or on your phone, and send it to me so that I can pass it on to the girls.
Please, give them the courage they need, and let them know that the world has not forgotten them.
If you haven't already, sign up for all our news here.