SAM Mitchell is making an explosive return to EastEnders as part of the soap’s Christmas storyline, we can reveal.

Actress Kim Medcalf is back to portray Grant and Phil’s feisty sister — and Sam’s return hinges on her rivalry with another of this year’s comeback characters, Zoe Slater.

Sam and Zoe’s friendship fractured over “Dirty Den” Watts’s murder in 2005 in a shocking storyline which saw Zoe flee Walford.

Now, 20 years on, the duo will be forced to come to terms with their past.

An insider said: “Walford has changed immensely since Sam left, most notably with enemy and ex-murder accomplice Zoe Slater now residing there.

“Zoe and Sam have not seen each other for over 20 years and as the enemies come face-to-face, only time will tell if the pair are willing to put their troubles aside, or if Sam has an ulterior motive.”

It’s no secret that wherever Sam Mitchell goes, drama inevitably follows

Ben Wadey, EastEnders’ executive producer

Michelle Ryan, 41, returned as Zoe in June — on a mission to find her son, who she gave up for adoption.

Rumours have since swirled Sam — once played by Danniella Westbrook — could return as part of Zoe’s comeback.

Kim, 51, said: “It’s such a joy to be asked to return to EastEnders, especially as it’s the festive period and there will always be plenty of fireworks.

“I love the character of Sam. She always causes drama wherever she goes, but she also has that vulnerable side too.

“It’s also lovely being back on set with the fantastic cast and to see old friends.”

Kim last appeared in January 2024 before the character left to chase her fortune abroad.

Ben Wadey, EastEnders’ executive producer, added: “It’s no secret that wherever Sam Mitchell goes, drama inevitably follows, and with ex-accomplice Zoe Slater back in the Square, only time will tell if there is space for forgiveness between the pair, or whether battle lines will be drawn.”

The murder of Den Watts was a huge storyline for the 20th anniversary of the BBC soap in 2005, involving Sam, Zoe and the real killer, Den’s wife Chrissie Watts.

The trio conspired to get revenge on Den, after he swept Zoe up in a blackmail plot and conned Sam into sex.

The women confronted him in the Queen Vic pub and when Den attacked Chrissie, Zoe intervened and struck him on the back of the head with a dog-shaped doorstop.

But after Sam and Zoe left, Den regained consciousness and grabbed Chrissie who then struck him again.

Sam secretly witnessed this final blow, but Zoe was left believing she was the killer.

Chrissie successfully framed Sam, who was charged with the murder before fleeing the country while out on bail.

Chrissie was eventually caught and admitted to the murder, exonerating Sam and Zoe. She was jailed for life.

HOW DEN MURDER UNFOLDED

SAM is best known for her role in the killing of Dirty Den, part of the soap’s 20th anniversary 2005 storyline.