Loyal Defender

There are little interfaces that look like robots that use emojis as a language. The people who visit the planet recieve little devices that look like mood indicators. When someone is really sad, then the interface sends out little nanobot-like robots called Vardies to strip them of their skin, down to the bone, killing them.

This is unsettling to me, since that means throughout the episode, you're left praying nothing happens for the Doctor and his companion to be put at risk of the same situation.