It's a stroke of genius to start things off with The Doctor telling a story of a creepy old house to an assassin. He tells the story of old acquaintances, a man who is shaking off the pressures of investigating a series of murders, the understanding but subtly undermined wife. Their friend, the host and owner of a seemingly cursed home.

It's serious and camp in equal measure and a world away from the story I thought they were going to tell as the final part of this trilogy (or fourth part of a quadrilogy?).

It slowly unravels that the house is bringing out the worst in the guests, the host has a secret identity and all this is more connected to the murders than we realised.

The Master is in such a deep disguise here that even he doesn't know he is himself, though unlike the similar reveal from Utopia (which came out 5 years later) he did not put himself into this state.

The Doctor crashes into this story whilst also remaining within the framing device of him telling the same story to the assassin. It's creates a neat rhythm across the 2 hours. We learn a dark secret from The Doctor's past with The Master which develops the brooding 7th Doctor.