The Secret in Vault 13 (novel)

 a novel released in 2018 by BBC Children's Books. It was written by David Solomons and featured the Thirteenth Doctor, Graham, Yaz and Ryan.

Publisher's summary
A sinister school where graduation means death...

A monstrous mystery lurking below a quiet London street...

A desperate plea for help delivered by... hang on. A potted plant?

The Doctor has been summoned. The galaxy is in terrible danger, and only a Time Lord can save it. But to do so, she must break in to an ancient vault on a remote and frozen world - from which nobody has ever returned alive...

Can the Doctor and her friends Yaz, Ryan and Graham uncover the shocking secret in Vault 13?

Plot
to be added

Characters

 * Thirteenth Doctor
 * Graham O'Brien
 * Yasmin Khan
 * Ryan Sinclair
 * Willow
 * Deadly Nightshade
 * Parsley
 * Lily of the Valley
 * Oak
 * Curatrix
 * The Attendant
 * Aaron
 * Lalitha
 * Porter
 * Space Lord Draal
 * Bernard
 * Hydran prisoner
 * Dalse prisoner
 * Chentan prisoner
 * Zraryx prisoner

Species

 * The Thirteenth Doctor has two hearts.
 * The Fleet conquered 10,000 star systems.
 * The Doctor previously defeated Sontarans, Cybermen and the Daleks of Skaro.
 * The Thirteenth Doctor encountered carnivorous chessmen on Proxima Ceti earlier.
 * Hydrans originate from Polaris Alpha.

Locations

 * Bernard pursues the Doctor, Graham, Ryan and Yaz through the Forest of Desolation, across the Burning Grounds and into the Valley of Agonies. It was sent from the Citadel in the Blasted Plains.
 * Bugbeasts live on Zeta Draconis.
 * The Fleet was planning to attack the Avolantis System.
 * The Fleet defeated Murgon III.

Individuals

 * Ryan thinks of Harry Houdini.
 * Space Lord Draal had the hull of a captured Frost Pirate warship and fins of megalovore sharks, which used to inhabit the Outland Sea, in his throne room.

Events
The Outland Sea boiled away during the Ice Cap Wars.

Continuity

 * The Thirteenth Doctor explains that the TARDIS is supposed to blend in with the environment using the chameleon circuit, but it got stuck in a form of a police box circa 1963. (TV: An Unearthly Child)
 * Graham O'Brien was most keen to leave Earth and travel with the Doctor. (TV: Arachnids in the UK)
 * Graham, Ryan and Yaz chose to leave Earth with the Doctor a few weeks ago. (TV: Arachnids in the UK)
 * Graham would not want to run into Ravenous monsters. Incidentally, Ravenous are especially feared by Time Lords. (AUDIO: Seizure)
 * The Doctor recalls how she and Sarah Jane Smith had problems with Krynoids. (TV: The Seeds of Doom)
 * Graham finds a tourist prospect for the Leisure Hive on Argolis, but the Doctor has already been there and had issues with the tachyon generator. (TV: The Leisure Hive)
 * Yasmin Khan never met Graham until their encounter with Tzim-Sha. (TV: The Woman Who Fell to Earth)
 * The Doctor recalls her encounters with Yeti robots. (TV: The Abominable Snowmen, The Web of Fear)