The actors and production crew are staying tight lipped on how it is going to end. Lead actor James Norton, who plays evil killer Tommy Lee Royce, used just six words: "Happy Valley. The finale. That’s all."
Con O'Neill who plays Neil Ackroyd in the Sunday primetime BBC drama that has the nation gripped would only tell This Morning's Holly and Phil that the ending blew his mind, describing it as "extraordinary".
With just days to go until the finale, the excitement is building and it seems like everyone has their own theory about what writer Sally Wainwright might have planned.
Read more: The 7 questions we need answering ahead of series' final episode
Will Sergeant Catherine Cawood (Sarah Lancashire) and her grandson Ryan (Rhys Connah) escape the clutches of psychopath Tommy Lee Royce? Another major loose end to tie up in the last ever episode is the murder of abused wife Joanna Hepworth, whose body was discovered in a suitcase with her husband framed for her murder by chemist Faisal Bhatti.
At the end of last Sunday's gripping episode, Tommy was hiding out after escaping from court as he prepared to stand trial for murder. Meanwhile his conflicted son Ryan found out the terrible truth that his killer father had raped his mum before he was born, and his granny Catherine had raised him despite the rest of the family not wanting him.
But he was still chatting with his dad, will he betray is father? Will he betray his grandmother? We have to wait until Sunday, February 5 to find out but here are some of the outlandish theories we have seen fans sharing this week:
1. One particularly 'unhappy' ending theory that a fan shared on Twitter was: "Tommy murders Ryan when he chooses Catherine over him. Faisel is cautioned over the tablets but lets slip about Joanna and is charged. Thug A is arrested at his wedding. The little girl uses her coat as a comforter. Catherine dies on the start of her retirement. The End."
2. Another is predicting the demise of Catherine's sister Clare: "Ryan is an idiot, thinks he’s going to save his dad, tells him where he is. Tommy kills Clare. Ryan FINALLY realises he’s not a nice man. Ryan kills Tommy. Catherine has to arrest him."
3. Another simply said: "Airport standoff, he goes to shoot Catherine and Clare intervenes and is killed."
4. Another fan thinks that Ryan is playing along with his dad: "Ryan goes along with Tommy's plan making Tommy believe he's leaving the country with him...there's a showdown with the police...final scenes with just Catherine Ryan and Tommy ...I'd like to think Catherine Richard and Ryan head off to the Himalayas! Pharmacist gets come uppence"
5. Another one thinks the teenager will take the side of good over evil: "Ryan grooms TLR while all the time surrounds him with UC cops and gets him arrested again. Catherine leaves HB for Himalayas and takes Ryan with her!"
6. This one is not good for fans of Ryan who want him to be able to go on and finish his GCSEs. One fan wrote: "I think Ryan decides to leave with Tommy but the police find out where Tommy is and Ryan gets killed in the crossfire. The pharmacist crumbles and gets charged and Catherine's sisters boyfriend turns out to be Tommy's dad."
7. The main picture used to advertise the show has Catherine, Tommy and Ryan as the only characters, which would back up this theory from one fan: "I think Ryans gonna help police corner Tommy or do something to show that he’s got his granny’s sense of duty and morals and not his dads traits. But I think it’ll backfire and there’ll be a showdown between Catherine and TLR where Ryan might beg her to spare his life."
8. Happy Valley superfan David Chipakupaku’s theory for the final is also based on the promotional advert. Writing on Twitter, he began: "++ Potential #HappyValley Spoilers! ++ Has the ending been staring us in the face all along?
"This is the artwork for series three, which was released more than a month ago. You can see the road bike Tommy uses circled (crassly) in red. And then, in blue…a massive fire …" Read more here.
But all fans must agree with Rachel Day who wrote on Twitter: "I know that whatever happens I won’t be disappointed. Amazing acting and plots throughout the whole 3 series. It just gets better and better."
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