Forced to flee the UK and go into hiding in the 1990s, when he became a mole from within the BNP, Matthew Collins returned to Britain to make a new life for himself, working with young white men in the fight against radicalisation.

The story of how Detective Superintendent Steve Fulcher deliberately breached police procedure and protocol to catch a killer, a decision that ultimately cost him his career and reputation.

Bull mysteriously returns home after a 10 year absence to seek revenge on those who double crossed him all those years ago.