Eagle-eyed Line of Duty fans have made a huge prediction...
Line of Duty fans are convinced a blink-and-you'll-miss-it moment from last night's episode could hold a huge clue for series six.
The first instalment of the new series was met with rave reviews last night, and already Line of Duty theories are flying around the internet.
But one that some fans might have missed is a brief throwback clue from series five.
Did you spot it?
About half way through episode one, DI Kate Fleming (Vicky McClure) went to Terry Boyle's flat while he was being questioned about the murder of journalist Gail Vella.
More: Who is H in Line of Duty? All the clues, theories and suspects so far
But as she got out of her car and flashed her badge to the officer on the door, fans spotted Kingsgate Printing Services in the background.
What is Kingsgate Printing Services?
Viewers who have watched series five of the crime drama will know that the shop featured heavily in the last series.
Kingsgate Printing Services was where undercover-cop-gone-rogue John Corbett met with associate Lisa McQueen and the rest of his organised crime group.
The OCG were using the shop as a front, secretly using it to print fake passports.
As Kate got out of her car she seemed to register the shop for a brief moment, and fans didn't miss a beat...
With the return of both Terry Boyle and the Kingsgate Printing Services there are plenty of past storylines cleverly being woven into the new series.
But could Kate's moment of recognition just be a nod to a past case she has worked on, or is there some more significance to the moment.
All Line of Duty fans know that every clue, suspect and shock twist has been carefully placed in each episode for a reason... so could it only be a matter of time before more past throwbacks are subtly revealed?
Line of Duty Season 6 airs Sunday nights on BBC One at 9pm. You can catch up on episodes after they have aired on BBC iPlayer.
