During a riot in England in 1985, police escorting firefighters to put out an inferno were attacked by a mob wielding machetes and molotov cocktails. Constable Keith Blakelock was set upon by at least 20 men, and murdered in the street, despite efforts of his fellow officers to save him. Now, 35 years and three trials later, we are no closer to finding the murderers. Who killed Constable Blakelock?