The border town of Reynosa is a battleground with drug cartels fighting for control of trafficking routes into the United States.

Juan Paullier joins the Mexican security forces on patrol of the most dangerous town along the US-Mexico border.

You can watch the full documentary Life in the Shadow of the Wall on BBC World News: Part one will in August 11 - 13 and part two in August 18 - 20.

In the UK it will be available on the iPlayer and on the BBC News Channel on these times:

Episode 1: Friday 11th - 2130 / Saturday 12th - 1330, 2030 / Sunday 13th - 0030, 1030, 1630

Episode 2: Friday 18th - 2130 / Saturday 19th - 1330, 2030 / Sunday 20th - 0030, 1030, 1630

Presented by Juan Paullier. Filmed and directed by Paul Harris.