Why gangs expand beyond their turf

Lucy was 13 when she was robbed by the drug gang she was working for and then stabbed as punishment. 

Now in her 20s and living in a refuge, Lucy was one of thousands of children exploited by violent drug gangs. 

A decade after authorities first identified the emergence of "county lines" dealing, parents and former child runners have spoken about the devastating impact on their lives. 

Niall is joined by Sky's home affairs editor Jason Farrell. 

Producer: Tom Gillespie 

Editor: Mike Bovill