If you watch enough television, you’ve probably learned to loathe these two little words: “bottle episode.” Such episodes are usually created primarily to save money, and the result is a crappy low-budget ep that audiences forget as soon as the credits roll. However, we were pleasantly surprised to see Doctor Who’s recent episode “Boom” pull off a bottle episode that might very well be the tightest Who story we’ve gotten in years.

Bottle Episodes

Before we can lavish praise on this Doctor Who episode, we need to answer the unspoken question some of you have: what’s a bottle episode? While critics and audiences quibble over the finer points of the definition, this generally refers to an episode that takes place entirely (or almost entirely) in a single setting and has very few guest stars.

Having very few locations and actors makes the episode cheaper to produce, and this generally allows the showrunner to throw more of the budget at a different episode (say, a show-stopping season finale).

Like most longrunning TV shows, Doctor Who has generated some pretty bad bottle episodes over time. Going back to the very first season of classic Who, “The Edge of Destruction” was a very boring episode made on the cheap explicitly because the first two serial adventures had gone over budget.

In the modern era of Doctor Who, “Love & Monsters” is a boring bottle episode often (and rightfully) described as one of the worst eps in the franchise.

A Wonderful, Tense Episode

Because of those previous Doctor Who adventures, I was pleasantly surprised at what a great bottle episode “Boom” turned out to be. For one thing, it had tension galore: the premise of this ep is that the Doctor has stepped on a high-tech landmine that he cannot safely get off of.

The stakes are high and the acting is stellar, and just having this kind of life-and-death plot involved helps “Boom” avoid the usually bottle ep problem–namely, having an ep filled with people having boring conversations in an equally boring room.

Character Growth

“Boom” writer Steven Moffatt (notably a previous Doctor Who showrunner) also wisely gives the bottle episode a different set of high stakes: emotional ones. We learn plenty more about the Doctor and how he reacts to imminent death, and we get a look at how surprisingly clearheaded and decisive Ruby Sunday can be in the lethal face of the unexpected.

Even the Anglican Marine supporting characters get revelations about everything from love to war, giving the episode an ambitious and expansive feeling that belies its small setting.

The Doctor Needed To Learn New Tricks

While we’re praising Moffatt, it’s also worth noting that he gave his Doctor Who bottle episode the familiar storytelling trapping fans expected while turning the franchise formula on its ear. For example, we have the Doctor and his trusty Companion working to solve a big mystery while allied with memorable supporting characters–all the ingredients of a classic Who story, right?

But as Moffatt said of writing this episode, trapping the Doctor on a landmine takes away his ability to run around (literally) or “bamboozle” anyone, forcing him to approach a classic Who dilemma using an entirely different set of tricks.

Making The Impossible Look Easy

So far, this initial Disney era of Doctor Who has been great, and seeing the show produce a killer bottle episode fills us with confidence for the rest of the season. For a franchise that has been around as long as this one, it’s important to find new ways to pull off old stories. And in making a bottle episode not only good but highly important to the show’s lore, this series took after its protagonist and made doing the impossible look downright easy.