Line Of Duty spoilers! Preview tonight's penultimate episode on BBC One

Line Of Duty is back tonight on BBC One for its latest and penultimate episode.

The hit police corruption drama returned for a fourth series earlier this month on its new home on BBC One.

When DCI Roz Huntley (Thandie Newton) captures a serial killer, Forensic Coordinator Tim Ifield (Jason Watkins) alerts AC-12 to a possible miscarriage of justice.

Series four of the hit drama, written and created by Jed Mercurio, started with DCI Roz Huntley and her team in the thick of a career-defining case, Operation Trapdoor.

Under intense pressure to catch the culprit and prove herself to her superiors, and facing conflict with her colleague, Forensic Coordinator Tim Ifield, it’s not long before AC-12 decide to probe her handling of the investigation.

A mother of two and wife to husband Nick (Lee Ingleby), Roz will do anything to stop her life unravelling. Anything.

In tonight's episode, AC-12's future hangs in the balance, after Hilton bars them from investigating Roz Huntley.

But Roz's problems are building closer to home.

Meanwhile, in this preview clip, Hastings confronts Hilton at Police HQ but Hilton turns the tables.

Line Of Duty airs tonight at 9PM on BBC One.

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