It’s time to get up to speed before the drama returns.
In the lead-up to Line Of Duty’s return for a fourth series, here is everything you need to know to get you up to speed.
After soaring to success with its first three series on BBC Two, it has now been promoted to BBC One – but star Vicky McClure said that, as far as the cast are concerned, it’s “business as usual”.
What happened last time?
In the series three finale, AC-12 (anti-corruption unit) finally caught up with devious DI Matthew Cottan (Craig Parkinson) as he was linked to paedophile mobster Tommy Hunter – finally freeing Steve Arnott (Martin Compston) from suspicion.
What happens now?
Pre-released teasers show an action-packed start as the new series begins with a dark abduction case. New star Thandie Newton takes the central role of DCI Roz Huntley, who is the first to face interrogation as suspicions arise over another corruption scheme.
Who else is new?
The Westworld star will be joined by a host of new faces, including Jason Watkins (playing forensic coordinator Tim Ifield), Claudia Jessie (DC Jodie Taylor), Mark Stobbart (DS Neil Twyler), Anneika Rose (Pc Farida Jatri), Lee Ingleby (Nick Huntley) and Scott Reid (Michael Farmer).
Who is returning?
Reprising their roles with AC-12 are The Replacement star Vicky, who will take up a promotion as DS Kate Fleming, Adrian Dunbar (Superintendent Ted Hastings), Martin Compston (DS Steve Arnott) and Maya Sondhi (Pc Maneet Bindra).
Who is behind the scenes?
The series was penned by Jed Mercurio, who has already revealed plans for a fifth series.
Line Of Duty returns at 9pm on Sunday on BBC One.