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Prepare to have your nails shredded again as anti-corruption officers Supt Ted Hastings, DS Steve Arnott and newly promoted DS Kate Fleming return to weed out more dodgy cops.

There are surprises galore in this cracking opener, which introduces us to AC-12’s latest adversary, DCI Roz Huntley (a brilliant Thandie Newton), who’s under suspicion over her handling of a serial-killer case.

Jason Watkins is equally sensational as finicky forensics co-ordinator Tim Ifield, who blows the whistle on Roz.

But who will be believed – and will viewers have any breath left after this episode’s shocking finale?

Welcome back, AC-12, we’ve missed you!