The Doctor is on a human colony on Christmas Day when a man comes looking for a surgeon. The Doctor decides that is close enough to ‘doctor’ (he’s not actually the right person) and follows him to a crashed spaceship.
On board the spaceship is River Song, who doesn’t recognise him. She doesn’t know about this latest face of his. She wants the surgeon to help with her husband, King Hydroflax, who has a gemstone stuck in his head which is killing him.
Of course, this is River Song, so she doesn’t really want to help her ‘husband’ – she wants the gemstone. Killing Hydroflax would appear to be the easiest way to get it.
This is one of the less serious episodes around – the guest stars are Greg Davies and Matt Lucas after all, two actors most known for comedy. It’s not really daft, but it is pretty light-hearted on the whole, especially with the conversation that River is having with the Doctor about the Doctor when she doesn’t know he is the Doctor. The Doctor also makes a wonderful speech about the TARDIS being bigger on the inside, when River Song takes him inside it – as who he is at that point, he isn’t supposed to know what the TARDIS is, and River is planning on borrowing it without his permission. Something she has apparently done a lot.
There is the common recent problem of the music sometimes drowning out the dialogue, which is a nuisance.