If you haven’t enjoyed the first two episodes of Jamaica Inn – and one look at a newspaper will give you the hint that a few people fall into that camp – then there’s nothing in the final part that will change your mind. So you may as well go outside and enjoy the fresh air.

But if you have enjoyed Jamaica Inn then Episode 3 is a fitting final piece in what has been a gritty, and most importantly, well-paced, drama. Not that it’s easy viewing, kicking off as it does with a prolonged mass drowning.

I said in the review for Episode 1 that Jamaica Inn feels like it was pulled up out of Nature’s grasp, and in fearful symmetry its finale features people being forced back down into it.

We begin with a grim but powerful scene in which Joss Merlyn and his salty backing group of wreckers lure a ship onto the rocks and then proceed to drown the survivors with the cool detachment of an abattoir worker three days away from retirement; plunging them beneath the waves, dragging their bodies shore, and picking them clean of all valuables. Joss and The Wreckettes are an unsettlingly practised band.

From there the intensity simmers along nicely as a post-heist mistrust develops. The Inn becomes increasingly claustrophobic; a metaphorcial prison of suspicion and lies that has Joss trapped, unlike the real prison that Jem Merlyn breaks out of in perhaps the most low-key jailbreak ever. 1821 chokey apparently only had one lock. Well, that’s the Earl of Liverpool’s Britain for you, innit, eh? Eh? ‘Tsch’.

Jem needs to find out who Joss is taking orders from. Wouldn’t you know it (and you would if you’ve read the book) Rev. Davey is the Mr Big behind the wrecking racket. He’s the Blofeld of boat-wrecking. The Lex Luthor of luring ships to their doom. Damnit Davey, only just last night I was calling you the most telegenic of the TV clergy and now you go and do this to me. Should’ve read the book, Rob…

Killing Joss and Patience, and then kidnapping Mary, Ben Daniels transitions seamlessly from friendly Father to foe. Yet he’s just a little too polished, too cool and controlled to be fully convincing as the pagan-worshipping, ship-wrecking mastermind that he’s so proud of being. There’s not quite enough zealotry and malice behind his crafty mind games as the words coming out of his mouth (and Emma Frost’s script continues to be terrific right to the end) might imply.

It’s a thrilling, if old-fashioned finale as Jem swashbuckles in to save Mary, who manages to avoid completely being painted as the damsel in distress by being forced to make a weighty decision placed on her by Davey. And in the best old-fashioned buckswashling tradition, the villain gets his comeuppance (or fall-downance) and Mary and Jem get a mercifully saccharine -free happy ever.

There’s less of a happy end for the show, however, the dramatic worth of which has been sadly overshadowed by audio problems on both the show’s end and some viewers’. People have complained loudly about things being too quiet. The irony is deafening, but it shouldn’t drown out all the good that has been accomplished here.

Aired at 9pm on Wednesday 23 April 2014 on BBC One.

> Follow Rob Smedley on Twitter.

What did you think of the episode? Let us know below…