Smile (Doctor Who)

In the episode, the Doctor (Peter Capaldi) and his new companion Bill Potts (Pearl Mackie) visit an off-Earth colony only to find it devoid of any life except for robots that communicate via emoji.

[a] The colony is empty except for millions of nanobots called the Vardy that maintain it, along with robotic avatars that interact with the pair via emoji.

Resolving to destroy the Vardy before the arrival of the unsuspecting colonists, the Doctor locates the ship that brought the pre-colony crew to the planet and plans on overloading its reactor.

However, Bill discovers a young boy who leads her to a large number of hibernation chambers including some humans just awaking; the Doctor realises that this is the colony ship.

Failing to dissuade them from fighting, the Doctor resolves the situation by "resetting" the Vardy to their original state, before they saw grief as a disease.

[3] The colony ship is named Erehwon, based on the work Erewhon: or, Over the Range by Samuel Butler; the story is of a man that finds a seemingly idealistic society but then turns away when he discovers there are harsh penalties for even slight offences.

[10] The episode was watched by 4.25 million viewers overnight, a slight decrease from the opener for the series, and came fourth in the ratings behind Britain's Got Talent, All Round to Mrs. Brown's and the FA Cup.

The website's consensus reads: "Though moments verge on the ridiculous and portions are bland, "Smile" grows compelling, fun, and chilling when focusing on two leading characters hanging out for much of the episode".

[15] Writing for IGN, Scott Collura also praised the Doctor's relationship with Bill, stating he's "totally sold on this new Doctor/Bill dynamic at this point, and this season's new direction as well."