First broadcast 13 April 2013.

The Doctor (Matt Smith) and Clara (Jenna Coleman) arrive on a Soviet submarine in the year 1983. The crew has uncovered an alien body under the ice, and when it is defrosted it reveals an Ice Warrior warlord from 5,000 years in the past.

As far as premises go, “Cold War” has a brilliant one. It brings back the Ice Warriors to Doctor Who for the first time since 1974. It situates them in a fresh and interesting context with huge potential for high drama and enormous tension. The submarine setting is a clever one, and it is actually a surprise it had never been done in the series before. The episode also benefits from one of the best supporting casts ever: not just Liam Cunningham (Game of Thrones) and David Warner (Time Bandits) but also Tobias Menzies (Outlander, Rome) and even future Hollywood star Josh O’Connor (Challengers) and a pre-Grantchester James Norton.

The episode is directed by Douglas Mackinnon, and written by Mark Gatiss. It is in that second appointment that the other shoe drops.

Gatiss is an accomplished actor and writer, and certainly in the script-writing department he has demonstrated enormous talent through his work on The League of Gentlemen, An Adventure in Space and Time, Sherlock, and current hit Bookish. When it comes to his work for Doctor Who, however, he seems to inevitably combine great high concept ideas with lacklustre, formulaic scripts. Daleks in World War II, aliens lurking in Victorian-era gas pipes or 1950s television signals, or haunted doll houses menacing children’s bedrooms are all great ideas for Doctor Who. In practice, they more or less disappoint. That is his problem here: putting an Ice Warrior on a Cold War era Soviet submarine is probably the best pitch Gatiss ever had for the series, yet the script is formulaic and dull.

There is a world of acting talent here without anything interesting to do. There is a legendary alien race from Doctor Who‘s past to rediscover, who exemplify the approach of making each individual one an actual character, and Gatiss – the first person beyond creator Brian Hayles to write for them – delivers something trite and simplistic. He emphasises an Ice Warrior obsession with honour, akin to Star Trek‘s Klingons; Hayles never made them so ordinary.

He also lets his particular Ice Warrior escape from its suit, in a somewhat silly plot excursion that the production values simply cannot match. The CGI is terribly unconvincing, and weakens the entire episode.

A surprising element is the episode’s treatment of Clara. For the first time the series ignores the “Impossible Girl” story arc and simply lets the character stand up for herself. It is the best she has been: funny, smart, brave, and well-rounded. A key scene has her having a moment of clarity about seeing dead bodies on a Russian submarine three years before she was born, and realising just how dangerous a situation she is actually in.

The ultimate issue with “Cold War” is not that it is bad; it is that it is bizarrely unadventurous. It can be frustrating watching an episode where so many elements are rich with potential, but so much of that creative possibility is left unexplored. It is not bad television. It is simply ordinary.