Line of Duty fans were stunned as the show came full circle in Sunday night's episode - with a revelation about series one character Jackie Laverty.
Viewers who have watched the hit crime drama since the very beginning will remember Jackie (Gina McKee) as the ill-fated lover of policeman Tony Gates.
She was brutally murdered by the OCG (organised crime group) and her body put into a freezer before being moved to Terry Boyle's flat.
Episode three of series six saw Boyle's missing freezer turning up in a scrapyard - and forensic results showing a blood deposit which is a 99.9% match for Jackie.
Her remains were found with those of John Corbett in the last series - and AC-12 now realise her body could have been stored in the freezer by the OCG for years.
Fans were impressed by the intricate plotting - even if it left some struggling to keep up with all the twists and turns.
Andrew McBride said on Twitter: "Jackie Laverty. Murdered in season one still relevant in season 6......"
Nigel Harris said: "With Jackie Laverty’s blood showing up in *that* freezer #LineOfDuty has achieved the longest Plot Arc yet....right back to season one!"
BovaryCee posted: "A connection to Jackie Laverty!!! I love when they circle back to previous storylines. I remember the scene where one of them opened the freezer for food/drink in Terry’s flat and the body was there."
slide_totheleft said: "It's funny watching everyone lose their mind at the Jackie Laverty connection as someone who's binged every single season in the last week, ur so 3000 and late."
