JACK Branning has been happily married to Denise Fox for less than a year following an explosive Christmas wedding.
However, the police officer shared a smooch with Sam Mitchell and EastEnders viewers believe they know who caught them.
The character played by Scott Maslen drowned his sorrows at Peggy's during last night's instalment of the BBC One soap.
While at the local wine bar, Jack's former fling Sam Mitchell (played by Kim Medcalf) made an appearance and she planted a kiss on him before he pulled away.
Sadly for Jack, there's more trouble ahead and, this time, it could wreak havoc within his marriage to Denise Fox.
A mystery enemy filmed the scene on their phone - but will Denise be shown the video?
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Viewers immediately jumped on Twitter to share their theories, believing they knew who was responsible.
Could the blonde scheming bombshell have anything to do with it?
According to viewers, there's more chance of Jack's daughter Amy or her boyfriend Denzel Danes (Jaden Ladega) being the culprit.
"So I'm guessing that was Amy or Denzel!" one viewer commented.
Another echoed: "Who caught the kissing cheating ones on camera? Maybe Denzel (or Amy)."
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One soap fan agreed: "def Denzel or Amy getting their revenge on Jack!"
The online theory wouldn't be too far-fetched as Amy has potentially compromised Jack's police career.
This followed a shocking moment during which the young girl, aged 13, made the decision to sleep with the lad - but the latter decided against it.
Yet a misunderstanding led to Jack believing the pair had been intimate which infuriated him.
In recent scenes of the long-running drama, Denise, her sister Kim and Denzel's father Howie all tried to calm Jack down as he held the youngster up against a wall.
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A fuming Amy got revenge on her father by reporting him to the police for the assault, leaving him heartbroken and walking on eggshells at work.
Amy retaliated because her father showed her no mercy, putting harsh punishments into place instead.
He most notably took her phone away and grounded her, despite Denise trying to calm him down.
When he was made aware of the report made against him, Jack firmly believed Howie was responsible until he found out Amy had completely turned her back on him.
This led him to head for the local boozer where he bumped into Sam.
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But after almost sabotaging his career, could Amy try to cause drama in Jack's marriage?
EastEnders airs from Monday to Thursday on BBC One.