There's plenty of fascinating material in this autobiographical film by English/Nigerian actor Adewale Akinnuoye-Agbaje, and yet it's presented so brutally it's hard to take the story in.
"Farming" refers to a common practice from the 1960s through to the 1990s, in which Nigerian immigrants would, on arrival in Britain, foster (or farm out) their children temporarily to white British parents, so they were able to complete the studies and work that would enable their families to have a better life in future.
Farming tells the story of Enitan (played as a boy by Zephan Amissah, and as a teenager by Damson Idris), who was farmed out to a working-class family in Tilbury, where his "mother" Ingrid (Beckinsale) would foster five or six kids at a time.
It was a tough upbringing for Enitan, with racism rife at home, school and on the street, and he grew up without a sense of identity, and a strong sense of self-hatred.
As a teenager in the 80s, Enitan is physically and verbally targeted by a white supremacist skinhead gang and, in a move that's not made understandable, goes on to join them, at first as a kind of mascot, and then as an active member, leading their assaults.