Roots: The works of Edgar Allan Poe, in particular The Raven, Berenice, The facts in the Case of M Valdemar, The Murders in the Rue Morgue, Tales of Mysteries and Imagination, The Black Cat (also quoted), The Premature Burial (also quoted), The Pit and the Pendulum, The Fall of the House of Usher (also the origin of the codename Roderick) , Ligeia, The Gold Bug, the poem "A Dream Within a Dream", and The Masque of the Red Death (Wendigo quotes from this). Bauhaus architecture, Goya, Senior Prosecutor Uglosi owes his name to Bela Lugosi. The Wendigo. The Doctor calls Tamsin "Stanislawski" while Tamsin calls Wendigo "The Wicked Witch of the West' (The Wizard of Oz) and refers obliquely to the popular defence of the Nuremberg trials ("zey vere only obeying orders.") The Doctor quotes Harry Houdini's supposed spirit message to his wife ("Rosabelle, believe!") Ghostbusters ("you have experience in Ghostbusting, then?). When the Levee Breaks, "They're Coming to take me Away" H P Lovecraft's "The Haunter of the Dark'. "You're back in the room"
Goofs: Tamsin doesn't know how to operate the TARDIS door control, despite it being one of the first controls she learns about inside the TARDIS in the previous story (and one of the last things she does in the story).
Double Entendres: "You are premature"
Continuity: The world 'Nevermore' was once Corinth Minor, a popular holiday world in the constellation of Cassiopeia. Its volcanoes showered semi-precious gemstones. The Earth military commander Verdeghast's enemy Morella Wendigo detonated a biological weapon in the planet's troposphere, and Corinth Minor's population asked for the aid of the Time Lords to the resulting, incurable Red Death which targets human DNA, forms in a mist and promotes cellular mutation. In answer the Time Lords transported the world through a cloud of supraviolet radiation, sterilising it, and as a memorial of the folly of war the planet was thereafter named Nevermore. Nobody has visited it in twenty years. All the survivors of Corinth Minor thus affected by the radiation are mutants - Berenice herself is able to project a form of herself as a creature formed from radiation. Technology includes helicopters. Humans of this time know of the Time Lords and are able to contact them.
A "strange little man" visited Uglosi and convinced him Verdeghast was plotting against him, an hinting that he would betray his people and create the Corinth Accord (?). [this is obviously the Monk] This is a class one temporal intervention.
Supraviolet radiation is bad for the eyes.
The TARDIS contains a gym, a sauna (which is standard issue), a greenhouse, beach (a maile of Margate, including extraordinary seagulls) and fliedershrews (see: Links)
Tamsin did a circus arts course at drama school.
Cats are revered on Gallifrey, and the traditional post of a Presidential cat was brought to an end by the Doctor's misadventures with genetically-engineered giant mice (see; Links). He says he was "taught by the king of handcuffs" (i.e. Harry Houdini), although he never got to double-loops. He thinks highly of Enid Blyton. He assumes the Master is no longer around.
Links: This story seemingly follows Situation Vacant (in which Tamsin also says she likes mochacinos) Relative Dimensions (Fliedershrews) The Mark of the Rani (presidential cats and the end of the tradition) The Doctor mentions temporal storms and the Villa Dioratti (The Company of Friends: Mary's Story) the Humanian Era (Doctor Who) and Houdini (Planet of the Spiders, et al)
Q.v. 'Who and Houdini'
Untelevised Adventures: The Doctor was in Baltimore in 1849 on "another errand" and, taken to be an actual Doctor, directed to the home of Edgar Allan Poe.
The Bottom Line: Good name. Apt. Story and stars take a back seat to simple box ticking as Alan Barnes purloins the canon of Poe to stitch together a take that's high in atmosphere, low on originality. There are some impressive set pieces here, but their success is due more to the source material and sound engineering. Even worse, for Tamsin's first outing we still know very little about her. And so it's a mess, really.