Happy Valley is about to reveal its dramatic ending this weekend - but what time is the last ever episode on TV, and who will star in it?
This is everything you need to know about the BBC One drama's finale.
When is Happy Valley's final episode on TV?
In a world of streaming services, it's a rare treat to get a TV show ending that everyone will watch at the same time.
Make sure you don't hit any spoilers for Happy Valley's last episode by tuning into BBC One at 9pm on Sunday.
Read more: Where is Happy Valley filmed?
The episode will run at 10 minutes longer than usual, finishing at 10.10pm, and will be available on iPlayer along with all three seasons.
Who are Happy Valley's cast and characters?
The pair have had a long-running animosity after Catherine's daughter Becky took her own life aged just 18 because she had been raped by Tommy and had his baby, Ryan (Rhys Connah).
After his release from his first prison sentence, Tommy tried to kill Catherine and poured petrol over Ryan, who was rescued at the last minute.
He also abducted, raped and planned to kill Ann Gallagher (Charlie Murphy) who was rescued by Catherine, and was eventually jailed for his crimes which included the brutal murder of a police officer.
Season three has seen Tommy break out of jail after fleeing a court appearance, with the aim of finally killing Catherine and getting Ryan to escape to Malaga with him.
An eight-year gap between seasons has meant that Connah has been able to return to his childhood role as a teen exploring his own feelings about his monstrous father.
Catherine's son Daniel (Karl Davies) is now in a relationship with Ann, who is a detective herself in Catherine's force, while her father, the wealthy businessman Nevison Gallagher (George Costigan) is still a close friend of the Cawood family.
Another of the drama's main characters is Catherine's former addict sister Clare (Siobhan Finneran) who she has fallen out with in series three after discovering that Clare and her boyfriend Neil Ackroyd (Con O'Neill) had been secretly taking Ryan to visit Tommy in prison.
Other key characters in season three include drugs gang boss Darius Knezevic (Alec Secareanu), and Catherine's ex-husband Richard (Derek Riddell).
Season three includes a related plot about the murder of prescription drug addict Joanna Hepworth (Mollie Winnard) who was killed by dodgy pharmacist Faisal Bhatti (Amit Shah) as he panicked about threats from the Knezevics, and her abusive husband Rob Hepworth (Mark Stanley) who the murder is being pinned on.
What will happen in the Happy Valley finale?
Fans of the series are speculating that either Catherine or Tommy will be killed off in the final episode of Happy Valley.
Tommy has been planning to go after Catherine as a final act of revenge, but she is determined to catch the escaped convict and has said in previous seasons that she has considered killing him.
Viewers are also hoping for a reconciliation between Catherine and sister Clare who betrayed her over the prison visits.
Meanwhile, it remains to be seen what side Ryan will come down on - he has been feeling rejected by the Cawoods, but seemed to have a greater understanding of what Tommy had done after some harsh words from Ann.
Watch: Happy Valley releases trailer for explosive last battle between Catherine and Tommy
With multiple endings reportedly filmed and theories swirling about what will become of the characters, it promises to be unmissable TV.
Norton said: "I think the reason this series is particularly exciting is because everyone knows it’s the last and so everyone is going to be waiting for something to happen, and everyone is sort of predicting and guessing how Sally wants to end it.
"I have been predicting for the last seven years how she is going to end it so it was really wonderful to read the script and hear her ideas - and they don’t disappoint."
Happy Valley concludes on Sunday at 9pm on BBC One.