Warning. This article contains spoilers for The Girl Before
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In Wednesday's conclusion viewers fans finally discovered the identity of Emma's (Jessica Plummer) killer.
In a flashback, Emma’s boyfriend Simon (Ben Hardy) revealed he had been sleeping in the service cupboard to “protect” her after the two break ins at the house.
But when Emma told him to leave, he flew into a rage as she attempted to walk away and call the police. Simon grabbed her by the neck neck before letting her fall to her death at the bottom of some concrete stairs.
In the present, Jane (played by Gugu Mbatha-Raw) had been conducting her own investigation into Emma’s death and when she invites Simon over for dinner, she soon realises he killed Emma. Simon then confesses he has fancied Jane ever since they met because she reminds him of his dead girlfriend.
He chases Jane upstairs to the secret room she found in previous episodes and in a frightening twist, he wraps his arms around her neck.
Simon grabs at her pearl necklace after she uses them to fight him off, but in the tussle he slips and falls to his death in the exact spot where Emma died.
While some fans thought the finale and Simon being unveiled as the brutal killer was thrilling, others thought it was disappointing.
One fan tweeted: "Well what a great last episode. Simon gets what he deserves!! Such a clever ending."
Another viewer shared: "Wow how fantastic was #TheGirlBefore brilliant acting, brilliant story & a brilliant twist - always said you can never trust someone called Simon."
And a third wrote: "And 3 years later history repeats itself with Simon dying the same way in the same spot Emma died."
They added: "I liked #TheGirlbefore it definitely got better as it went along."
However some people weren't impressed. "If that’s the twist then what a disappointment #TheGirlBefore," one fan tweeted.
While a second person shared: "I thought the finale of #TheGirlBefore was a little bit of an anti- climax what’s everyone else’s thoughts??"
A third wrote: "Meh, they just gonna make it Simon then? I hope not #TheGirlBefore."
And another Twitter user chimed in, writing: "Making Simon the bad guy is really cheap after all the set up with the house and women, I’m regretting wasting my time on this. #TheGirlBefore."
Despite the mixed reaction to the finale, fans praised the series overall.
The four-episode series follows Jane Cavendish who falls in love with a unique minimalist house with incredibly cheap rent.
However, living in the house means she is forced to abide by the strict rules of enigmatic architect Edward (David Oyelowo).
Things soon take a weird turn for Jane, after she discovers Emma Matthews (Jessica Plummer), someone who had previously lived in the property, had been found dead there.
After the first episode aired on BBC One on Sunday night,, one person gushed about the new series, writing: “Excellent cast, great staging (at last, the menacing modern house plot really feels like an atmospheric location, not a studio set) - it’s creepy and stylish.
“I’ll try not to binge the rest of it tonight, but verrrry tempted!”
You can now binge watch all the episodes on BBC iPlayer now.