There are a plethora of words you could use to describe the final episode of Being Human‘s triumphant fourth run: ‘Intense’, ‘Moving’, ‘AAAAAAHH!’, and likely all will be employed liberally by fans, because this is a series finale they’ll be talking about for a long, long time.

If you’ve invested the time and emotion that this series has deserved, The War Child will reward you handsomely for your devotion… and emotionally punish you for being human (sorry) enough to care about the characters in it.

For the past seven weeks you’ve watched them, loved them, and maybe even leered over them (*cough* shirtless Hal *cough*). Now you’ll be put through the wringer as you see each one forced to do heroic, terrible things to protect the people they love.

Everyone is tested, and through the struggle and the portent of apocalypse come great performances from all: Annie as a mother, Tom as a warrior, Alex as a ghost, Cutler as an ambitious beast, Hal as a… well, what is Hal? Hero or villain? Whichever path he chooses it seems he’s destined to suffer. So will that path be with Tom and Annie, or the malevolent Mr. Snow?

The marvellous Mark Gatiss pours his love of horror into his portrayal of Mr. Snow, a decaying Old One who’s part Hammer Horror relic and part rotting monster. His serpentine performance matches the snake-like nature of his character: tempting Hal with forbidden fruit and savouring each acidic line with the joy of a python eating Christmas dinner. Part of you will be terrified by him, part of you will be seduced by him. That’s the whole point. It’s a chiller thriller of a role.

But the most terrifying aspect of proceedings is a choice that you, like Annie, must entertain in your head: let Humanity be dragged kicking and screaming to the slaughterhouse, or know that a baby will be murdered. It’s a bizarre feeling; a purposefully unsettling and uncomfortable experience to be put through as a viewer, and it makes the tension all the more unbearable.

Lenora Crichlow cannot be faulted for the work she does in this episode. We’ve talked a lot about what the new boys have brought over the course of the series but Crichlow has been the vital component throughout the transition; a reassuring, motherly, presence to fans wary of change.

Her performance here traverses the entire topography of emotion; depths of despair, peaks of humour, culminating in an Annie line so perfect, so typically Being Human, that we wouldn’t dare spoil it for you.

And amidst the terrific blender blur of humour and terror that is Toby Whithouse’s script, there’s something brand new and very old coming into focus; sharp-suited and organised to the millisecond, and with unclear but unusual motives. It’s just one of several fresh threads neatly spun from the drama; a tantalising tease that may remind you of Mr. Kemp and the Series 1 finale.

Heart-breaking and heroic, The War Child is perhaps the best finale the show has accomplished, and the perfect end, thematically and emotionally, to a series that has been all about change; about letting go of the old and the beloved and the wicked, and accepting the new.

More than that, it marks the bold new direction that the show has taken. And we can’t wait to see where that will take us in Series 5. Because surely, after a series of such high quality, this can’t be the end. Can it?

Airs at 9pm on Sunday 25th March 2012 on BBC Three.

> Order the Series 4 DVD on Amazon.

Are you looking forward to the episode? Let us know below…