In a new trailer released by EastEnders it looks like Ronnie (Samantha Womack) has gone to the dark side again.

The video, to promote the Monday, June 23 episode, opens on a light note, with Ronnie’s dancing around the kitchen to the song Walking on Sunshine.

But we hear Roxy (Rita Simons) telling Aleks (Kristian Kiehling) that “she’s always been a few sandwiches short of a picnic”, and it’s clear that all is not as happy as it seems.

Then Phil’s at the front door, asking, “Is Ronnie here?”.

“She’s upstairs. Has something happened, Phil?” Roxy asks, sounding concerned.

And something must have happened – or be about to happen – as it’s clear that Phil (Steve McFadden) is not there for a social visit. He says nothing as he heads upstairs.

In Ronnie’s bedroom, Ronnie and Phil are sitting on her bed and Ronnie says to Phil, “You’ve got to have back-up”.

“What do you mean?” asks Phil.

Yes, what do you mean, Ronnie?

Ronnie reaches into her bedside table and pulls out a gun.

“I don’t think I know who you are any more,” Phil tells her.

“I’m a Mitchell, Phil.” says Ronnie, with the gun in her hands. “I’m a Mitchell.”

What is Ronnie’s secret? asks the trailer.

Has she used that gun already? Or is she planning to use it?

Click here to see video.

EastEnders hour-long special, BBC1, Monday, June 23, 8.00pm