A quick Google search on the phrase “thin ice” reveals a situation of possible danger or risk, where the “ice” could break at any time and the person treading or walking on it could fall in. It usually implies that the walker knows they’re putting themselves at risk, but is continuing nevertheless.

This weekend’s episode, written by Sarah Dollard (“Face The Raven,” Series 9), is aptly titled “Thin Ice.” Not only is it set during the last London Frost Fair on the River Thames in 1814, but our heroes also snap up the opportunity to expose themselves to risk, both emotionally and physically. The Doctor is no stranger to trouble. After all, his travel machine is “a bad girl […], always looking for” it. He’s also seizing yet another chance to leave the confines of his university office and vault-guarding responsibilities.

Oy, the vault. More on that, later.

So. The Thames has a monster, a loch-less whale-like monster, if you will, chained beneath the surface, kept for the purpose of producing excrement that burns as fuel anywhere, under any environmental conditions. A school of angler fish bait food for the monster in the form of unwitting humans who are attracted to the lights dangling off the anglers’ heads, visible from above the thin sheet of ice onto which they’ve strayed. It is the death of one human, a child/street urchin named Spider, that creates tension between The Doctor and Bill in this episode. Unsurprisingly, Bill is horrified that The Doctor allowed Spider to drown and be consumed by the monster, which leads to an exchange that ends with The Doctor pushing back:

You know what happens if I don’t move on? More people die. There are kids living rough near here. They may well be next on the menu. Do you want to help me? Do you want to stand here stamping your foot? Because let me tell you something. I’m two thousand years old, and I have never had the time for the luxury of outrage.

If the end point of Doctor Who is to educate as well as entertain, then we must add “Thin Ice” to the list of episodes that deserve repeated viewings. Sarah Dollard handles racism, privilege, and the value of life in all forms with a deft pen. Bill is empowered by The Doctor to decide how they will proceed, and she rises to the challenge. My love and appreciation for her as the new companion is, seriously, boundless.

Now, the vault.

Whatever is in there, is very much alive, and is making its presence known. Listen very carefully to the sounds it makes.

Rating: 9/10 servings of gingerbread and gin

Next week: David Suchet.