This was a two-part Twelfth Doctor story from Series 9 in 2015, set in the early 22nd century in a base under a Scottish reservoir, and also in 1980, in the abandoned village that was there before the reservoir was built. I don’t appear to have written it up at the time – I was a bit sparing when the last name on the screen was my first cousin, which may have been too cautious of me.
The TARDIS, with the Twelfth Doctor and Clara on board, arrives in the year 2119, in an underwater base under siege from ghosts, which appear linked with a mysterious alien vessel at the bottom of the lake. The crew of the base start getting picked off one by one. The Doctor goes back to 1980 to try and sort things out, but apparently returns as a ghost. The trouble is being caused by a semi-dead alien called the Fisher King, but I confess I did not really follow that part. Eventually all is resolved with the use of time paradoxes – the Doctor has a breaking-the-fourth-wall conversation with the viewer about who really wrote Beethoven’s music. There are some very good shots of Capaldi in particular.

Notably, Cass, the woman who takes command of the crew for most of the story (after the original commander is an early victim) is deaf, played by deaf actor Sophie Leigh Stone, and communicates with everyone else by signing through an interpreter.
I also noted with interest that two characters played by actors of Asian heritage, Zarqa Ismail and Arsher Ali, are given the thoroughly Anglo names Tim Lunn and Mason Bennett. (I don’t think we ever find out Cass’s first name.)
The writer was Toby Whitehouse, who also wrote School Reunion, one of my favorite New Who episodes; Greeks Bearing Gifts, one of my favourite Torchwood episodes; the series Being Human; and the New Who episode The God Complex, which I didn’t rate as highly and have written up here along with its Black Archive.
Rewatching Under the Lake / Before the Flood, I would rank it as average or slightly below. Over on X/Twitter, it did better, at 120th of 309 Who stories in @heraldofcreatio’s poll. Anne could not remember having seen it first time round. I find the plot decently sfnal and the base well realised, but the energy somehow not quite there, and the means and motivation of the alien menace obscure. Full marks of course for the portrayal of Cass’s disability, which we’ll get back to.
Ryan C. Parrey and Kevin S. Decker have done a solid though relatively short Black Archive on the story. The first chapter is an introduction which briefly touches on bases under siege, evil capitalism, and the reversed sequence of the narrative.
The second and longest chapter, “The Bootstrap Paradox”, goes in detail into the exploration of time paradoxes in this story and in other Doctor Who stories, and the extent to which they also carry the freight of moral dilemmas.
The third chapter, “‘Only Room for One Me’”, looks at Clara’s arc overall in the wider Doctor Who narrative. Its second paragraph is:
“This two-part story contributes important elements to Clara’s arc during her time with the 12th Doctor, an arc that begins before Danny’s death and that sees Clara act on her fascination with the Doctor’s power and responsibility. Making a conscious decision to leave certain inhibitions behind after Danny dies, she experiments here and elsewhere in series nine with, in effect, becoming the Doctor.
Incidentally I am writing this at Gallifrey One, where Jenna Coleman as usual is charming the participants.
The very brief fourth chapter, “Ghosts in the Machine”, looks at the ghosts in the story as compared to other Who stories, and unpacks how they are not really ghosts.
The fifth chapter, “New Waste Lands”, which is also short, looks at the alien Fisher King and successfully explained to me what is actually going on in the story, better than the script did.
The sixth and best chapter, “The Case of Cass”, looks at the varying ways that disabled people are portrayed in the media, especially in Doctor Who, coming to the conclusion that Cass is uniquely well depicted in this story. Hard to disagree with that, and it’s well argued.
The seventh and concluding chapter takes us back to ethics and invokes Jean-Paul Sartre.
I rate this about average of the Black Archives, but with significant bonus points for the discussion of disability. You can get it here.
The Black Archives
1st Doctor: The Edge of Destruction (67) | Marco Polo (18) | The Aztecs (71) | The Myth Makers (65) | The Dalek Invasion of Earth (30) | The Romans (32) | The Massacre (2)
2nd Doctor: The Underwater Menace (40) | The Evil of the Daleks (11) | The Mind Robber (7)
3rd Doctor: Doctor Who and the Silurians (39) | The Ambassadors of Death (3) | The Dæmons (26) | Carnival of Monsters (16) | The Time Warrior (24) | Invasion of the Dinosaurs (55)
4th Doctor: Pyramids of Mars (12) | The Hand of Fear (53) | The Deadly Assassin (45) | The Face of Evil (27) | The Robots of Death (43) | Talons of Weng-Chiang (58) | Horror of Fang Rock (33) | Image of the Fendahl (5) | The Sun Makers (60) | The Stones of Blood (47) | Full Circle (15) | Warriors’ Gate (31)
5th Doctor: Kinda (62) | Black Orchid (8) | Earthshock (51) | The Awakening (46)
6th Doctor: Vengeance on Varos (41) | Timelash (35) | The Ultimate Foe (14)
7th Doctor: Paradise Towers (61) | The Happiness Patrol (68) | The Greatest Show in the Galaxy (66) | Battlefield (34) | The Curse of Fenric (23) | Ghost Light (6)
8th Doctor: The Movie (25) | The Night of the Doctor (49)
Other Doctor: Scream of the Shalka (10)
9th Doctor: Rose (1) | Dalek (54)
10th Doctor: The Impossible Planet / The Satan Pit (17) | Love & Monsters (28) | Human Nature / The Family of Blood (13) | The Sound of Drums / Last of the Time Lords (38) | Silence in the Library / The Forest of the Dead (72) | Midnight (69)
11th Doctor: The Eleventh Hour (19) | Vincent and the Doctor (57) | The Pandorica Opens / The Big Bang (44) | The Impossible Astronaut / Day of the Moon (29) | The God Complex (9) | The Rings of Akhaten (42) | Day of the Doctor (50)
12th Doctor: Listen (36) | Kill the Moon (59) | Under the Lake / Before the Flood (73) | The Girl Who Died (64) | Dark Water / Death in Heaven (4) | Face the Raven (20) | Heaven Sent (21) | Hell Bent (22)
13th Doctor: Arachnids in the UK (48) | Kerblam! (37) | The Battle of Ranskoor av Kolos (52) | The Haunting of Villa Diodati (56) | Ascension of the Cybermen / The Timeless Children (70) | Flux (63)