Although our world would come crashing down if Line of Duty's Ted Hastings turned out to be as bent as the coppers he's supposedly investigating, the fourth series' finale left us doubting the motive of the show's stalwart.
But Lee Ingleby – who played the troubled lawyer husband Nick Huntley to Thandie Newton's corrupt copper Roz in the last series – has reminded us that we can never second guess writer and master manipulator Jed Mercurio.
"I know everyone thinks Ted Hastings could be corrupt, but it's really hard to second guess because with Jed," the A Word actor told Digital Spy, "you think you have a handle on it, and then he pulls the rug from under your feet.
"You're left with a completely different answer than you thought you had. I'm not going to second guess. I never get it right... I have no idea!"
Viewers had their suspicions about Hastings when the last series revisited the dying declaration of dodgy 'Dot' Cottan (Craig Parkinson). Before he died, he hinted at a figure heading up a network of corrupt officers, a senior officer above the rank of Inspector who was identified with the initial 'H'.
Hastings – who usually does things to the letter of the law – was happy to conclude it was ACC Hilton (Paul Higgins) following Hilton's suspected suicide. But Hilton had pointed the finger at Hastings.
The series then ended with an ominous shot of Hastings looking suspect and quite literally behind bars.
Meanwhile, Mercurio says he never closes the door on a living character, and although Ingleby's Nick isn't returning for series five, he could be back in the future.
"That's what happened in the third series, there were some characters returning from the first and second series so who knows... As it stands in the current filming, I'm not involved. It was very much a closed book on that family but you never know.
"I think it's different for Roz unless she's escaped from prison. The mind of Jed – who knows."
Roz was sentenced to 10 years in prison for murdering forensic investigator Tim Ifield and perverting the course of justice, but is still married to Nick.
On Line of Duty's recent casting of Stephen Graham as AC-12's latest person of interest in series 5, Ingleby added: "He's such a great actor - he always deliver intense powerful performances. It's a great choice.
"I'll be really intrigued to see where it goes... I think it will be another brilliant addition to the juggernaut that is Line of Duty."
Line of Duty's series 5 will return to the BBC next year.
Line of Duty Season 4 premieres on Sony Crime Channel on November 21 and will air every Sunday at 9pm. Sony Crime Channel is available on Freeview 40, Sky 157, Freesat 143 and Virgin 193.
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