Line of Duty

After Sergeant Danny Waldron and his armed response team shoot dead a hardened criminal, cracks begin to appear in their story and AC-12 is assigned to investigate.

After the shooting at the drugs house, DC Fleming uses her undercover role to increase the pressure on Waldron's armed response unit.

DS Arnott believes Waldron compiled a list of his childhood abusers, but DI Cottan's commendable investigation casts a long shadow over his efforts.

Fresh testimony puts AC-12 back on the trail of "the Caddy," a corrupt cop with links to organized crime.

AC-12 faces divided loyalties when Arnott is suspended from duty.

Arnott is arrested on suspicion of murder, and DC Fleming's undercover operation may hold the key to his innocence and the identity of the mysterious perp.