'Line of Duty's series six finale will "break hearts".
Craig Parkinson, who played Matthew 'Dot' Cottan in the BBC series, praised the show as "iconic" but warned that fans will be devastated with the revelations in the upcoming last episode.
Speaking on the Sky podcast 'Backstage', Craig said: "I'm so proud of the guys for going back after the break [when the COVID-19 pandemic forced filming to halt], getting it done without any illness and delivering one of the iconic great British dramas that we've produced in the past few years.
"Talk about timing, we all need AC-12 in our life right now, albeit I'm sure they're going to break some hearts at some point."
Craig - who hosts his own 'Line of Duty' podcast, also spoke about the crazy theories he has heard about the show and the identity of the mysterious H.
He said: "I'm watching things in advance of the rest of the nation, I'm having to watch things two or three times, I'm forensically dissecting these episodes, my social media timeline is awash with the maddest of theories you could possibly imagine.
"The fandom has built slowly and steadily over the years, and they are obsessive. I have friends that have been in 'Doctor Who' and they talk about the 'Doctor Who' fans - I mean, the 'Line Of Duty' fans are up there with their devotion and their love for these characters.
"It's kind of amazing if I'm honest, I'm certainly not slagging them off, you know. We wouldn't be anywhere without them - and I'm one of them."