Proving its chops as a thoughtful science fiction show, the latest Doctor Who blends a quirky sci-fi premise with deadly serious commentary on the dangers of extreme capitalism. Dying in outer space is awful, but it’s made way worse when oxygen has become currency. And if that wasn’t enough, the episode ended with a huge twist that will change the rest of the season in a big way.

Spoilers ahead of Doctor Who Season 10, Episode 5, “Oxygen.”

The first words uttered by the Doctor in the latest episode are “Space … the final frontier.” This is an appropriate Star Trek homage because this adventure does what Trek is famous for: using action-packed science fiction as a critique of society as we know it. When the TARDIS responds to a distress call, the Doctor, Bill, and Nardole find a space station where a mining company rations oxygen as a way of controlling its workers. The Doctor dismissively calls this set-up “capitalism in space,” which turns out to be 100 percent accurate.

Refreshingly, there aren’t any goofy aliens causing the problems in this episode. Instead, the self-aware “smart suits” are killing off the workers on the space station on purpose. A mysterious company has actually designed everything this way, turning its employees into disposable commodities and occasionally paying them back with the breaths that they take. The Doctor fixes all of it, of course, by using capitalism against the smart suits. But, in saving Bill and the other workers, the Doctor makes a huge sacrifice.

'Doctor Who,' Episode 5, "Oxygen"

The big news of this episode is easily the fact that because he’s exposed to the vacuum of space, the Doctor is blinded midway through the story. Though Nardole uses some kind of gizmo to “fix” his eyes, the Doctor reveals in the final moments of the episode that it didn’t work, and he’s still blind. And just like that, the slow burn of Doctor Who Season 10 suddenly got way more interesting.

Flying blind, the Doctor has a lot happening all of the sudden. The trailer for the next episode — “Extremis” — seems to confirm the return of the Pyrovile volcano aliens from the Season 4 episode “The Fires of Pompeii.” There’s a glimpse of the Doctor’s diary in this footage, too, reminding fans of River Song and teasing a deep-dive into his past. Notably, this is the second time the Capaldi era has referenced “The Fires of Pompeii.” In Season 9, the Doctor flashes back to his David Tennant days during the episode “The Woman Who Lived.”

The final shot in the UK version of the new trailer also gives a glimpse of Missy (Michelle Gomez) lending credence to the fan theory that she is totally the person being hidden in the mysterious vault. Though, it could still be someone else entirely.


Doctor Who Season 10 airs on BBC and BBC America on Saturdays at 9 p.m. Eastern.

See also: How a Poem From 1681 Might Explain Doctor Who Mysteries

Photos via BBC America