General (Brigadier) Alistair Lethbridge-Stewart has retired and convinced his wife, Doris, to buy him a boat for Christmas. On Christmas Eve, whilst Doris is doing some late-night shopping, Alistair takes the boat out for a pre-Christmas test drive (unbeknownst to his wife). During his trip, Alistair spots a young girl in the water. Taking her back to his house, an argument ensues with the recently returned Doris over whether they should call the emergency services or whether Alistair should deal with the situation himself. Their disagreement is interrupted by the arrival of an old man looking for his granddaughter. Despite never meeting this incarnation, Alistair Lethbridge-Stewart believes that the old man is the Doctor.