Oh God the plotting is dreadful, and only gets worse. There is a particularly egregrious example later in the second series (the code word is "tingle"). I like Mary when she's at her nastiest, though*. And Edith. Actually, Edith is about the one vaguely plausible example of character development in the whole thing. She is crying out to join Peter's Cattery.

The actor who plays Bates appears to be making a career out of moralising. What on earth is Anna supposed to see in him? A psychopath who has hypnotised/terrified her with his evil wiles makes the most sense by far.

*Or with Carson, a relationship that's a great idea, but never quite developed enough.