Emmerdale viewers were left speculating they knew who Mackenzie Boyd had cheated on Charity Dingle with, after a cryptic scene on Friday night.
His mystery fling sent him messages and called him in the latest episode, causing him to tell them to back off.
But it was something he said that confirmed the mystery character was known to viewers, and lived in the village.
Fans now believe they know who Mack slept with after hearing him on the phone, and they are convinced it is someone very familiar.
Mack and Charity had a huge row during Thursday's episode, as Mack repeated to Charity that he wanted to try for a baby with her, following their recent loss after Charity suffered an ectopic pregnancy.
As Charity told him it wasn't what she wanted and that she might not fall pregnant again, Mack didn't listen and instead suggested they looked into IVF.
Charity ended up having a go at Mack, leading to him storming off and getting drunk.
Towards the end of the episode he was seen in bed with the unknown person, with only her arm and hand shown to viewers.
As he checked his phone and saw the missed calls from Charity, he smirked when the mystery woman knocked his phone out of his hand, before the pair got steamy again.
While the unknown female was not shown on camera in full, viewers did see her arm and her hand and they believed they were able to work out her identity.
But there were new clues in the latest episode, as Mack tried to hide his guilt from Charity as they reconciled.
Mack initially received a message from a mystery number, that read: "Need to see you."
Later, Mack grew panicked when the person called his phone, leading to him telling them to leave him alone.
He shouted: "Why are you hassling me? No, we don't need to talk about it. We need to forget about it and when we see each other at The Wooly, we need to act like it never happened."
While they may have exchanged numbers the night before, it could be someone that already has his number - while her name wasn't saved as a contact.
The mention of The Woolpack suggests she is a regular customer there who knows the village well, and very likely lives there.
Mack's comment suggested they will bump into each other more than once, which is awkward given Charity owns the pub.
Viewers now think the mystery woman is either Belle or Chas Dingle, both linked to Charity. Chas is already having an affair with Al Chapman, and Belle has made it clear she's not happy about it - but this hasn't stopped fans questioning if one of them are Mack's mystery woman.
Initial speculation suggested Chloe Harris was the one in bed with Mack, and while many fans are still convinced over this others have changed their minds.
Taking to Twitter, one fan said: "Omg I’m thinking it was Chas now," as a second said: "Could be Chas who Mack slept with I s’pose."
Another wrote: "What if Mack really did sleep with Chas?"
A fourth fan tweeted: "so who was the mysterious woman he had a 1 night stand with? She’s local & maybe single. I’m thinking Belle for some reason."
Another tweet read: "I believe it was either Belle."
Emmerdale airs weeknights at 7:30pm on ITV, with an hour-long episode on Thursdays.
