Detective Constable Steve Arnott is a fictional character from the British television series Line of Duty. He works for the Anti-Corruption Unit and is known for his dedication to uncovering police misconduct. His character is portrayed by actor Martin Compston. Arnott is characterized by his strong moral compass and determination to seek justice, often facing challenges from both criminals and corrupt colleagues. Throughout the series, he navigates complex investigations and personal dilemmas, making him a central figure in the show's exploration of police integrity and accountability.