Donna is shocked when her estranged father Derek (Clarke Peters) is admitted to the hospital and diagnosed with cancer. He dies soon thereafter, and when dealing with his effects, Donna learns that he unknowingly fathered another daughter. Though her half-sister is recently deceased, Donna meets her half-niece Mia (Jada Wallace-Mitchell), who is being raised by her grandmother, Patti (Barbara Drennan). Within weeks, Patti also dies, and Donna decides to adopt Mia. She and her friend Maria (Phoebe Thomas) compete for a ward sister position on the general surgery ward. Although Maria is the successful applicant, she realises that Donna needs the job in order to support Mia, and withdraws her candidacy so Donna is appointed sister. Donna falls in love with agency nurse Kieran Callaghan (Barry Sloane), and is devastated when he is called to serve in Afghanistan with the Territorial Army (TA). Kieran asks her to marry him, but Donna refuses, terminating their relationship with the intention of giving Mia stability. When Kieran is injured by an improvised explosive device (IED), Donna reconsiders, supporting him through the amputation of his leg. Upon learning that he will be transferred to a rehabilitation unit in Liverpool, Donna resigns in order to move there with him.