Actress Sophie Thompson - the sister of Nanny McPhee star Emma Thompson - is to join the cast of EastEnders.
Thompson starred in the 1996 film of Jane Austen's Emma
Thompson, who has also carved out her own successful career in films like Four Weddings and a Funeral and Gosford Park, will play lawyer Stella Crawford.
An EastEnders spokeswoman said Stella "has secrets to hide" from the other residents of Walford.
Thompson, 44, said she was "very excited" about joining the BBC One soap later this year.
She said: "Joining EastEnders is a bit like being welcomed into a really special playground that you never thought you had the chance to play in, and you are rather in awe of all the kids but very excited."
Thompson's best known role was as Lydia in the film Four Weddings and a Funeral, alongside Hugh Grant.
She has also starred in a number of TV dramas, including Casualty, Midsommer Murders and Jonathan Creek.