Memory and nostalgia has been something the Doctor rarely thinks about. However, when he lands in Crook Marsham in the late 60's, he and Ace discover that the town is being terrorised by an unknown force, as the citizens have been falling prey to their old memories. With the help of the locals, including a retired sci-fi actor, the Doctor attempts to discover why people's memories are coming back to haunt them. And he's not immune to it...
- Big Bad: The Sentience.
- Book-Ends: At the beginning of the story, The Doctor wants to stay in Crook Marsham. At the end, it's Ace.
- Borrowed Catchphrase: Trevithick uses the Second Doctor's "When I say run, run!" catchphrase, rounding off his odd similarities with the Doctor.
- ...But I Play One on TV: In universe. Trevithick initially wants nothing to do with solving the mysteries around Crook Marsham, but after getting some inspiration from his old Nightshade serials, he decides to help the Doctor solve them.
- The Call Knows Where You Live: In the audio, The Doctor gets rather irritated that his retirement spot is the target of an alien.
- The Cameo: Susan only appears briefly at the end of the story as a manifestation of The Sentience.
- Foreshadowing: The Doctor and Ace's conversation at the beginning of the story about "putting down roots" forshadows Susan's reappearance later and Ace decision to stay in Crook Marsham .
- Expy: Trevithick and his show Nightshade has more than a few similarities to Doctor Who and the actors who played the main character. Most notably, he's a crotchety old man with a soft spot for a science fiction show he worked on decades ago, like William Hartnell. He also bears a strong resemblance to one of the Doctor's direct antecedents, Bernard Quatermass.
- Genre Savvy: Trevithick certainly is. He's acted in Hammer Horror films before, so he knows how to avoid Plot-Induced Stupidity the characters he played fell for.
- Heroic Sacrifice: Trevithick sacrifices his life so the Doctor can avoid The Sentience.
- Let's Split Up, Gang!: Defied by Trevithick. After acting in horror films, he knows he's in a horror story and what would happen if he agreed to this idea.
- Lotus-Eater Machine: Nostalgia that kills.
- Not That Kind of Doctor: Double Subverted. A character is injured so another asks for the Doctor's help. He quotes this trope before deciding to help him anyway.
- OOC Is Serious Business: Ace is alarmed when The Doctor wants to stay in Crook Marsham forever.
- Surrounded by Idiots: Hawthorne thinks so, but he's wrong.
- Swiss Cheese Security: The radio telescope, to Hawthorne's annoyance.
Tropes specific to the audio adaptation:
- Advertised Extra: Carole Ann Ford as Susan! She only appears as a cameo at the end of the story, but is the sole guest listed on the front cover.
- In the audio, the Doctor points out that Ace "moans a lot when you're hungry!", similar to an observance he made of her in "Remembrance of the Daleks".
- The First Doctor's farewell speech to Susan was recreated word-for-word by the Seventh Doctor when he's reminiscing about losing Susan to summon her.
- I Choose to Stay: Ace tries to pull this at the end, before realising that a side-effect of The Sentience's influence over the town is wanting to pull this off.
- Leaning on the Fourth Wall: The audio version begins with a fake warning about the episode of Nightshade played throughout the serial, based on the one that originally ran before episodes of Quatermass And The Pit. It also serves to give Mark Gatiss a Creator Cameo.Announcer: Before we begin, we would like to say that in our opinion, the following presentation is not suitable for children or for those of you who may have a nervous disposition.
[Doctor Who theme plays]
- Show Within a Show: Nightshade, and bits of it are played throughout the serial.