Line of Duty fans spotted a crucial problem with Kate Fleming as series six of the BBC drama started.
Kate has a history of being undercover and as tonight's show started it appeared she was again, as she was working with a unit that viewers hadn't seen before.
But Kate was using her real name, causing confusion among fans who also wondered if she'd left AC:12 to move to a different department.
If she was undercover though viewers were quick to spot an issue.
Many people pointed out that Kate had been undercover so many times, that surely by now lots of police officers would know who she was.
Lots of fans said that Kate being undercover again was "unrealistic" and lots of them took to social media to comment on it.
Mounah said: "Is Kate undercover AGAIN? Everyone knows your face hun, it’s not realistic."
RH said: "Surely everyone in the police force knows that Kate works for AC-12 by now. Undercover for the 88th time."
Jonny Twiss said: "How many times can Kate go undercover without the whole police force knowing who she is?"
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H said: "How is Kate still doing undercover work doesn’t everyone know her face by now."
And Hastings said: "How many times can one person go undercover."
*Line of Duty continues at 9pm on BBC1 next Sunday
