And what a moment of Toby Whithouse genius it is too HalGal!

I am such a Being Human geek saddo that I know the whole spooky nursery rhyme by heart (I think)

"What’s that barking?

It’s all starting,

like a row,

of dominoes,

Can you stop them falling,

Someone’s due a mauling,

Here it comes,

The wolf shaped gun.

Annie listen,

Here’s your mission,

Mitchell’s toast,

If you’re a scaredy ghost,

Come to purgatory,

Stop shit getting gory,

Or a big bow-wow,

Ends his story now"

 ~ Toby Whitehouse ~

source

How right you are HalGal, when we first saw this we thought the dominoes reference was just a metaphor or symbol.... and although we have now literally seen the significance of dominoes for Hal in series 4, and the potential consequences of them falling, Hal was rescued (from himself ) by Annie! whether that is just a nice circle, or if it is a portent of even bigger things to come in the new series...and the dominoes represent something larger...who knows...but I certainly feel there is a lot  more to know about Hal...some deeper, darker things....and a lot more to come for him too!

Weirdly, quite a few people around me in RL and online have talked to me about this episode recently, having either rewatched it (again!) or seeing it for the first time... counselling the latter through the losing Mitchell trauma...but I have reassured them that all will be well. VERY WELL. in terms of loveable..mesmeric... hot vampire in the next series!

And Sami..there is nothing wrong with the way your beautiful noggin works!