"And a Merry Christmas to all you at home!
The Doctor and Steven land on a snowy mountainside, covered in pine trees. When they stumble into cottage with a scared young girl and her dying grandfather, however, things take a turn for the worse. For Greta's father is nowhere to be found, and the trees are getting closer.'O Tannenbaum' contains examples of the following:
- Christmas Episode
- Half-Human Hybrid: Joseph is, at least partially, turned into a pine tree. The Doctor can't fix it, and it doesn't seem to set him back too much.
- Titled After the Song
- Translator Microbes: The Doctor can speak tree. Alien Pine tree, at least. Steven, however, can't.
- When Trees Attack
