The latest episode was the sixth series’ most talked-about to date, featuring a huge shoot-out scene and a cliffhanger ending revealing that Jo Davidson (Kelly Macdonald) is in fact the blood relative of some as-yet-unidentified figure, presumed to be from the series’ past.
Writing on Instagram, Compston, who plays Steve Arnott on the show, claimed that viewers will “need therapy” after watching Line of Duty’s next instalment.
“Episode 5 kicks off as stores re-open and there’s a sale on waistcoats,” he joked, referring to his character’s penchant for the clothing item.
“In all seriousness though if you thought Ep 4 ended on a cliffhanger, you’ll need therapy by the end of Ep5,” he added.
Since episode four aired last Sunday (11 April), viewers have tried to piece together the mystery of Davidson’s relative, with a number of potential candidates all seeming plausible.
The BBC has already confirmed that one star from the series’ past is set to return for the next episode: Anna Maxwell Martin, who played DCS Patricia Carmichael in season five.
Another high-profile guest star also reportedly leaked on the BBC website earlier this week, prompting a response from Line of Duty’s creator, Jed Mercurio.
Line of Duty continues at 9pm on Sunday 18 April on BBC One.
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