To Mark's (Maxwell Caulfield) horror, Faye - played by Kim Thomson - descends on the community unexpectedly and he is forced to do everything in his power to prevent wife Natasha (Amanda Donohoe) from discovering her true identity.
With his marriage and family life at stake, Mark embarks on an ongoing battle to safeguard his future, while Faye carefully plots her next sequence of moves.
Of her casting, Thomson said: "I'm delighted to be joining the cast of Emmerdale. Faye is going to turn out to be a very interesting character to play, especially when the truth starts to come out!"
New series producer Gavin Blyth added: "Mark is going to get the shock of his life when he comes face-to-face with the mysterious Faye. He'll do whatever it takes to safeguard his relationship with Natasha and their kids, with explosive consequences."
In the soap, Mark and Natasha moved to the village in January after becoming tired of the high-rolling city lifestyle. Their children Nathan (Lyndon Ogbourne), Maisie (Alice Coulthard) and Will (Oscar Lloyd) are to join them in the country in a fortnight's time.
Thomson begins filming in Leeds later this month and will appear on screen from Monday, March 16.
Last month, Anita Turner stepped down as series producer at the ITV soap after only a year in office. Gavin Blyth was subsequently announced as her successor.
Executive producer of 24 years Keith Richardson, meanwhile, handed the reins to former Coronation Street exec Steve Frost.