year she starred in the three part ITV thriller, The Guilty, as Claire Reid, mother to a missing five-year-old child. In 2014 she played Alaura Kingsley in the critically acclaimed production of City of Angels at the Donmar Warehouse directed by Josie Rourke. In August 2015 it was announced that Kelly would join the cast of Happy Valley, which aired the following year. In the series Kelly portrays DI Jodie Shackleton, a part that was written for her by series creator Sally Wainwright. Kelly enjoyed the opportunity to play a character in her native Yorkshire accent, and prepared for the role by shadowing police detectives in Halifax. Also in 2016 she appeared as the Permanent Secretary in four episodes of The Night Manager. On 4 April 2016, it was announced that Kelly would appear in the BBC Three Doctor Who spin-off series Class written by Patrick Ness, airing from October 2016. In October 2016, Kelly appeared as Hannah in ITV drama Him. In 2018, Kelly made her first film appearance since 2009 in Dirty God, playing Lisa, the protagonist Jade's mother. The following year, Kelly appeared in the feature film Official Secrets, based on the real life events of intelligence whistleblower Katharine Gun (portrayed by Keira Knightley). In the film, Kelly plays Jacqueline Jones, an MI6 agent who tacitly confirms the legitimacy of Gun's leaked memo to a journalist contact at The Observer. The same year, Kelly appeared in an episode of Flack, as Brooke. Later that year, Kelly portrayed Leah in four part ITV drama Cheat. She plays DI Karen Renton in the second series of Liar for ITV/Two Brothers Pictures. In September, 2019, Netflix released its mini-series Criminal: UK with Kelly in the role of the lead investigator. Kelly joined the cast of Liar for its second series in 2020, playing Detective Karen Renton. A character bio for Renton describes her as an “unconventional” officer, whose “bluntness” often ruffles feathers. Of her role, Kelly stated “It's my belief that Karen Renton is that way because she has to be that, and if she wasn't that, I wouldn't believe that out of all the detectives that they could send from the Met to solve this front-page news story, why would they pick her if she wasn't excellent at her job?," she said. “I think she would have been chosen because she can act very quickly and very swiftly, and