The Doctor meets up with River Song on a planet known for its population of ghosts. Even the ghosts are disappearing, and a strange mist seems to be responsible. They meet other survivors who are also being pursued by the mist, and the pair of travelers find that there is a deeper truth to be uncovered that could have them question of the nature of their existence.
This turned out to have some interesting twists. The banter between the Doctor and River Song remains as quick and amusing as ever. There are some moments that evoke the appropriate sense of the spooks. It’s a strange yet solidly entertaining episode.