DS Steve Arnott is a fictional character from the British television series Line of Duty. He serves as a Detective Sergeant in the Anti-Corruption Unit, where he investigates police misconduct and corruption within the force. Known for his strong moral compass, Arnott often faces ethical dilemmas in his pursuit of justice. Throughout the series, DS Arnott is portrayed by actor Martin Compston. His character is recognized for his determination and commitment to uncovering the truth, even when it puts him at odds with colleagues and superiors. Arnott's journey highlights the complexities of law enforcement and the challenges of maintaining integrity.