The episode is set in a Scottish underwater mining facility in 2119, where the Twelfth Doctor (Peter Capaldi) and his companion Clara Oswald (Jenna Coleman) arrive three days after the crew have unearthed an empty spacecraft in the lake.
[2] The episode was watched by 5.63 million viewers and received positive reviews from television critics, with praise directed to the atmosphere, old-fashioned style and the cliffhanger.
The Twelfth Doctor and Clara arrive later via the TARDIS and are briefed by acting commander Cass, who is deaf and assisted by her interpreter Lunn.
The ghosts manipulate the electrical systems of the base and separate Clara, Cass, and Lunn from the Doctor and crew members O'Donnell and Bennett.
[5][8] The Doctor mentions meeting Shirley Bassey[3][7] and reveals that he is not a fan of Peter Andre's "Mysterious Girl": after suffering a two-week earworm of the song, he "was begging for the brush of death's merciful hand.
"[8] The "Readthrough Draft" of the script for this episode, glimpsed in the online "Doctor Who Extra" focusing on Cass & Lunn, was titled "Ghost in the Machine".
[11] Much like the previous episode, the lower ratings were possibly due to the England v Australia match in the 2015 Rugby World Cup airing simultaneously.
The site's consensus reads "Part one of two, "Under the Lake" scares up a good, old-fashioned ghost story, which may remind viewers of the original series – for better or worse".
Gloomy visuals and a haunting score from Murray Gold also do much to generate atmosphere and tension" and closed his review stating "Chills, action, adventure – this is old-school Doctor Who given a modern sheen and, most of all, it's enormous fun".
He closed his review by claiming "Forty minutes flew by and the credits rolled too soon, leaving on a creepy cliffhanger that left me baying for more.
[25] Jon Cooper of The Independent lavished praised onto the episode, calling it "spooky with a sci-fi slant" and saying that "while the show has tackled this sort of narrative countless times before, it has rarely been done with such palpable tension and slow-burning dread".
He further stated "As secrets were uncovered and deductions made, the plot rattled along with a pace that ended up as satisfying as it was intriguing", and closed his review by saying "in terms of wonderfully solid and spooky TV there’s nothing to moan about here".