David Tennant is so good at narrating that it still felt like there was a full cast here! Each character had a distinct voice both in writing and in performance, which really helped keep everything clear. I could really see this as an episode for 10. Akin to Midnight in setting but with a ghostly tone, it follows the two parter formula quite well with all the mystery and questions set up for part one so that we can run through the action in 2. I did not see the twists coming especially the one relating to The Doctor. Stopped me in my tracks. Great writing. I look forward to hearing more Tennant narrated adventures.