Duncan is appointed to look after Jin Jié after Kovic brings him and Hannah to the Valkyrie via helicopter from Shanghai, as well as processing refugees brought aboard by Irish. Her voice is first heard in the intro to South China Sea speaking with Garrison about the refugees. She first appears later on in South China Sea, arguing with Hannah about the status of Jin Jié. Throughout the rest of the campaign, she speaks to Garrison about the status of the Valkyrie and her patient in the introductory scenes of missions. She is last seen in Suez tending to Jin Jié alongside Garrison, Hannah and Tombstone squad when the Valkyrie is boarded. As she stays behind on the ship, her survival is determined by player choice; if the Valkyrie is destroyed or not.
Duncan's character model.
Her name is revealed in Countdown to War. In Battlefield 4, she is only referred to as "Doc" in the subtitles.
Despite what her uniform depicts, Garrison states that she is a lieutenant.