November 27, 2014 - 12:38 GMT hellomagazine.com Rita Ora stars in a series of new stills released of the Fifty Shades of Grey cast Fifty Shades of Grey fans were treated to a series of new stills of the film's cast on Wednesday, including pop star Rita Ora who plays Christian Grey's adopted sister in the highly anticipated movie. On the day that Rita was celebrating her 24th birthday, Universal Pictures released a photo of her in character as Mia Grey."Happy Birthday, @RitaOra!" posted the film's official Twitter account. "Rita Ora is Mia Grey, Christian's lively and vivacious little sister. #FiftyShades." Happy Birthday, @RitaOra! Rita Ora is Mia Grey, Christian's lively and vivacious little sister. #FiftyShades pic.twitter.com/DTu5cgx6hJ — Fifty Shades of Grey (@FiftyShades) November 26, 2014 As well as the image of Kosovo-born Rita, stills of Marcia Gay Harden, Andrew Airlie and Eloise Mumford in their roles have also been revealed. Oscar-winner Marcia and Fantastic Four actor Andrew play Christian and Mia Grey's adoptive parents, Dr. Grace Trevelyan Grey and Carrick Grey, while Eloise, who starred alongside Miley Cyrus in 2012 film So Undercover, stars as Anastasia Steele's best friend Kate Kavanagh. It's time to meet the parents. Marcia Gay Harden @Beloving2 and Andrew Airlie. #FiftyShades pic.twitter.com/C40siCnvlO — Fifty Shades of Grey (@FiftyShades) November 25, 2014 R.I.P. singer Rita joined the film's cast in December 2013. The British star announced that she would be playing Mia, alongside Jamie Dornan's Christian, while she was attending the British Fashion Awards. "It's official!," the excited songstress wrote. "I've been cast in @FiftyShades of Grey as Christian's sister Mia." Where would Ana be without her BFF? @eloise_mumford is Kate Kavanagh. #FiftyShades pic.twitter.com/TeaYpzIrot — Fifty Shades of Grey (@FiftyShades) November 27, 2014 While Rita is known for her musical releases, she studied acting at the Sylvia Young Theatre School and previously appeared in the 2004 film Spivs and Fast & Furious 6, alongside the late Paul Walker. A year and a half after it was announced that British director Sam Taylor-Wood would be behind the highly-anticipated screen adaptation of E. L. James' hit book, Fifty Shades of Grey will hit cinemas. The film, which is the first of the Fifty Shades trilogy, is due for release on Valentine's Day 2015.