[6] Mercurio wrote all 36 episodes and serves as an executive producer alongside Simon Heath and Stephen Wright.

[10] The series primarily follows the actions of Anti-Corruption Unit 12 (AC-12), a task force located within the fictional Central Police Constabulary.

[12] Martin Compston and Vicky McClure also starred in all six series as AC-12 officers Steve Arnott and Kate Fleming.

[27] Over the course of the series, an overarching storyline develops that connects numerous characters to an organised crime group which is found to be in a large conspiracy with high-ranking officers of the police department.

[28] Viewing figures increased significantly over the course of the series,[29] leading to record-breaking broadcasts[30][31] and causing it to become the subject of critical acclaim[32][33][34][35] as well as gaining a cult following.