Alice O'Donnell

Alice O'Donnell was the systems technician on board the Drum, an underwater mining facility in Scotland. She was a big fan of UNIT and the Doctor's work with them, and was thrilled when the Twelfth Doctor finally arrived.

When the Doctor laid a trap for the ghosts of both their former commanding officer Moran and a Tivolian named Prentis, O'Donnell and Cass stayed back in the control room. O'Donnell was in charge of opening and closing doors so that the other crewmembers could successfully escape the ghosts and lead them to their next target.

When the Doctor decided to travel back to before the flood to uncover the mystery behind the ghosts, O'Donnell and Mason Bennett were the only ones able to get back to the TARDIS with him, and the two journeyed with him back in time. (TV: Under the Lake)