THE final episode of the hit BBC series Happy Valley airs this evening - and it promises to end in a dramatic fashion.

The drama, which was first broadcast in 2014, has become a must-watch for the nation.

Episode one of this third and final series attracted more than 11 million viewers.

Tension has been building throughout this series, leaving viewers on the edge of their seats in anticipation of how the series will end - and it's all going to come to a head this evening.

The final episode, broadcast on BBC One tonight (February 5) will begin at the usual time at 9pm but will be 10 minutes longer.

Sarah Lancashire resumed her role as Sergeant Catherine Cawood for the final series.

Bradford Telegraph and Argus: Catherine Cawood, played by Sarah Lancashire, pictured on duty during the final episode of Happy ValleyCatherine Cawood, played by Sarah Lancashire, pictured on duty during the final episode of Happy Valley (Image: BBC/Lookout Point/Matt Squire)

In the first episode, Catherine discovered the remains of a gangland murder victim in a drained reservoir, sparking a chain of events that unwittingly led her straight back to the evil Tommy Lee Royce, played by James Norton.

The BBC has released some teaser photographs and a dramatic trailer featuring some of the show’s central characters ahead of tonight's episode.

Bradford Telegraph and Argus: Faisal Bhatti, played by Amit Shah, looks concerned during episode sixFaisal Bhatti, played by Amit Shah, looks concerned during episode six (Image: BBC/lookout Point/Matt Squire)

The teaser for episode six says: “Scores are settled for good on Catherine’s final shift, and Ryan faces a moral dilemma.”

Tommy Lee is still at large after breaking out of the dock during an appearance in Leeds court - and he wants revenge on Catherine. 

In the last episode, he was dropped off at a house by gang leader Darius Knezevic, played by Alec Secareanu, and viewers saw him chatting with his son Ryan. 

Earlier, a plan for Tommy Lee and Ryan to escape to Spain had been discussed, but will Ryan betray his grandma Catherine for a life on the run?

Bradford Telegraph and Argus: Sergeant Catherine Cawood looking through a photo album during the last-ever episode of Happy ValleySergeant Catherine Cawood looking through a photo album during the last-ever episode of Happy Valley (Image: BBC/Lookout Point/Matt Squire)

The teaser photographs also feature pharmacist Faisal Bhatti, played by Amit Shah.

He had been illegally supplying Joanna Hepworth, played by Mollie Winnard, with diazepam.

The pair had hatched a plan to murder her abusive husband Rob, played by Mark Stanley, but Faisal turned on Joanna and killed her before hiding her body in a suitcase. 

Eyes instantly turn to Rob, so it remains to be seen if Faisal will be brought to justice for his crimes. 

In one photograph, Catherine is seen at a police scene in uniform and in another, crying in plain clothes.

Will there be a happy ending in the not-so-Happy Valley?

Bradford Telegraph and Argus: Clare Cartwright, played by Siobhan Finneran, also looks concerned in Sunday's night's finale Clare Cartwright, played by Siobhan Finneran, also looks concerned in Sunday's night's finale (Image: BBC/Lookout Point/Matt Squire)

Some scenes for the third series were filmed in the Thornton area of Bradford and eagle-eyes viewers may have spotted some familiar sights in episode four as Clare, played by Siobhan Finneran, spoke to Catherine on the phone.

There was excitement last year when the well-known actress was spotted in the village as filming got underway.

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