EastEnders teased a twist was on the way on Thursday night ahead of the special flashback episode focussing on the Mitchells.
It's been hinted that Phil Mitchell's long-time nemesis DCI Keeble is linked to the flashback, with fans speculating something from the past has led to her determination to bring down the soap family.
But a scene on Thursday night left viewers stunned, as Keeble made it clear there was one person she wanted Phil to grass on, and tell her "everything he knew" about them.
Viewers didn't see who she was referring to, as she passed Phil a brown envelope containing a photo of the individual.
As he pulled it out he seemed shocked and immediately refused to give her what she wanted, while viewers only saw part of the picture.
It's not been confirmed who Keeble and Phil were talking about, but fans took to Twitter to share their predictions - and a few names have topped the list.
Keeble had asked Phil to give her information on a list of old associates of his in return for keeping him out of prison.
But she was furious when he instead warned all the names on the list that they were at risk, causing them to flee.
Phil then challenged her, pointing out she must have an ulterior motive for what she's asked of him and he wanted answers.
It's then that she told him there was one person she wanted information on before handing him the photo.
Fans immediately questioned if the photo was of his brother Grant Mitchell, amid hopes of a return.
Both of the brothers will appear in the flashback episode, set in 1979, and now fans think the episode will give away something huge about the Mitchells' past, and it might be linked to Keeble.
Taking to Twitter, one fan said: "I think Keeble wants information on Grant."
This was echoed by another viewer who said: "I think it's Grant in the photo," as a third tweet read: "Gotta be Grant in that photo."
EastEnders airs Mondays to Thursdays at 7:30pm on BBC One and BBC iPlayer.
