“My heart starts to go into palpitations around 10 o’clock on a Sunday night,” says Damien Molony. “I’m sitting on the couch and holding onto the armrest – in nerves, but also anticipation and excitement.
If the Being Human star is usually pumped up before the supernatural drama airs, he’ll be doubly so tonight. Not only does the episode mark the culmination of this season’s story arc – about the return to power of the Devil himself (albeit in the body of Phil Davis's dirty, sweary old pensioner Captain Hatch) – it’s also the last ever episode of BBC3’s supernatural houseshare. It deserves to go out with a bang.
Without giving anything away, Molony says the finale is "epic": "I really think [creator] Toby [Whithouse] and the writers have given it the ending it deserves… It’s a great way to go out."
Although he knows what happens, Molony, who plays OCD vampire Hal, will be in a similar position to viewers, seeing the finale unfold on screen for the first time. "I haven’t seen the episodes, so I’m just as excited as you are to see what they look like," he says – adding that he’ll likely be on Twitter beforehand helping to ramp up the excitement for fans.
"I always try to give a teaser before the episode. And it’s lovely to get people’s messages in the couple of days afterwards, to see how much they enjoyed certain moments. That’s lovely, to be able to communicate with fans like that."
Molony is well aware of the faithful following Being Human has been able to rely on (it's sustained audiences of a million or more for the majority of its run – huge for a digital channel like BBC3). "On Twitter, or coming to the stage door at the theatre [Molony is currently performing at the Royal Court in London], fans have been saying how sad they are that it’s finished. It’s sad for them and sad for us, but it’s lovely that people have such fond feelings for the show."
Being Human has run for five series and while there have been key personnel changes along the way, the basic premise – a vampire, werewolf and ghost share a house, and battle against inner and outer demons in an attempt to live normal lives – has remained the same.
Molony joined in series four, replacing Aidan Turner’s brooding vampire Mitchell, and joining Michael Socha’s werewolf Tom, who came to the fore following the departure of lycanthropic counterpart Russell Tovey. The pair co-habited for a series with original ghost Annie (Lenora Crichlow) who departed for the afterlife before current resident spook Alex (Kate Bracken) materialized in the last moments of series four.
Molony's character Hal is a 500-year-old vampire (one of the last of the so-called Old Ones) who imposes ruthless (and often hilarious) routines on himself – strict cleaning rotas, entirely white jigsaw puzzles – in an attempt to suppress his craving for blood.
The current trio have been together for just a single series (running two episodes shorter than previous seasons) yet their chemistry – in a show which relies on the mixture of pathos and deadpan humour generated by its three main protagonists – has been evident from the start, making them as much of a hit with fans as the original line-up.
Molony says their onscreen chemistry comes from a combination of Whithouse’s writing and his co-stars' talent, but also their offscreen friendships.
"Michael’s just a fantastic actor, but when we’re not filming the two of us have great craic too," says the Irish star. "It was great when Kate joined us, she just slotted in so perfectly, so when we weren’t filming we were playing games in trailers and running around set causing mischief.
"It didn’t take any time at all for the three of us to gel. It’s great to hear that chemistry comes across on camera.”
In fact, Molony and Socha hit it off from the start to such an extent that people have been bandying the B word – bromance – around...
"My second round audition for Being Human was to read with Michael on camera. I was in the room for about ten minutes, but we just seemed to click," says Molony.
"We didn't really see each other for another couple of months and then we started filming, and it just kind of worked. I’m not going to say that it was love at first sight, but it was that kind of connection that we had.
"The two characters hate each other to begin with and over time it develops into this ‘bromance’, as people call it."
As the series draws to a close, that bromance looks to be in mortal danger. Hal is back on the blood and a tooled-up Tom is hunting him, believing he has murdered his new girlfriend, mostly thanks to the scheming of Captain Hatch.
Being Human has a history of pitting its housemates against one another before resolving their differences and, despite the dark twists and turns it takes, it's hard to imagine that a show which is essentially about the power of friendship would finish with those bonds in tatters. Whether all ends well is, of course, a different matter but Molony is focusing on the positives.
"Toby's had the chance to write a climax that Being Human deserved... It’s sad to see it go, but I have such amazing memories of my two years and I was so honoured and delighted to be given a character like Hal to play with.
"I’ll miss it, but I think it’s probably the right time for it to end."
The last ever episode of Being Human is at 10pm tonight on BBC3