1983, during the Cold War. A Russian sub has unearthed something in the artic-unfortunately that something is an Ice Warrior-the Martian race who have served as both enemy and ally to the Doctor in the past. It starts to rampage across the ship.
However, the Doctor and Clara arrive, although they intended to go to Las Vegas.
He attempts to barter a peace between the Warrior-Shaldak-but the Warrior is not interested in peace, as he’s been encased for 5000 years and has lost his family and his species has resettled elsewhere in the galaxy. They manage to hold the Warrior prisoner, but he manages to escape, giving us our first look at what the creatures look like outside their armor-kind of reptilian.
Sheldak plans to set off the nukes on the sub, creating a nuclear war for revenge against humanity. Thankfully however, his people arrive to take him home, and he deactives the missiles.
Next up, the Doctor and Clara visit a “haunted” house where a psychic and a researcher are trying to contact a ‘ghost’.
The Doctor soon figures out that this isn’t quite a ghost, but something else entirely-a time traveller, moving at an incredibly slow speed, trapped in another dimension.
The Doctor then starts a rescue operation of sorts, by hooking the psychic to one of those blue Metebellis III crystals that caused him a lot of trouble at the end of his third life.
The Doctor is able to rescue Hila (who is actually a future descendant of the researcher and psychic, who have feelings for each other), although he himself gets stuck for a bit, and pursued by an unusual looking creature. After getting out of the dimension with help from Clara and the TARDIS, the Doctor figures out the creature was kind of just looking for it’s mate, which was in the house, and reunites the monsters.