Line of Duty fans discover first-look clip after following clues hidden in season 6 trailer

Clever fans spotted that a magazine cover featured briefly in the trailer includes a QR code and that scanning the code with your phone unlocks a Line of Duty Easter egg – a letter from Philip Osborne, Chief Constable (Owen Teale) to DCC Andrea Wise (Elizabeth Rider), addressing his concerns about AC-12 and, in particular, their leader, Ted Hastings (Adrian Dunbar).

But the fun doesn't stop there – aficionados of the series (who really deserve a position at AC-12 themselves) discovered a link in the PDF letter document which leads to another document - this time a medical report relating to DS Steve Arnott (Martin Compston), which contains a message in morse code...

We won't reveal the entire clue trail here - that'd spoil the fun! - but we will say that it's worth persevering with this particular investigation, as your ultimate reward will be an exciting clip from the new series featuring Arnott, who may be considering leaving AC-12 behind... gasp!

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The clip also features scenes of a tense stand-off between armed police and a man in a balaclava (sound familiar?) with DCI Joanne Davidson (this series' guest lead Kelly Macdonald) and DI Kate Fleming (Vicky McClure) caught in the middle.

If a trailer drop is this thrilling and surprising, we can't wait to see what the series itself has in store...

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Line of Duty returns on Sunday, 21st March at 9pm on BBC One. Take a look at the rest of our Drama coverage, or check out what else is on with our TV Guide.