Nails hammered under fingernails, castration, nipples filleted from flesh, electrocution, rape… “This really did push the limits,” confirms special effects co-ordinator Paul Hyett, best known for his gore-ific work on The Descent. “What we were shooting was pretty extreme.” No, this isn’t Saw V, it’s WAZ (pronounced ‘W delta Z’, but affectionately labelled ‘WAZ’ by its cast and crew). A moody, feverish film populated with stark imagery and hard-bitten performances, it’s the debut feature for British director Tom Shankland. And rumour has it that it contains some of the most horrific, brutally violent images ever put to screen.

Shot in Belfast and New York over six weeks in May and June 2006, WAZ traces its roots back to the Darwinist theories of George Price. An American population geneticist, Price formulated an equation – WAZ = Cov – that appeared to disprove the existence of selflessness, heroism or love in nature. “How do you tell a love story within the most brutalised, violent landscape?” postures Shankland, who worked on the script with former film school buddy Clive Bradley. “That was the conflict in this film. What happens to the idea of love, or the possibility of love with this amount of damage and violence?”

Damage is the key word in WAZ. Set in a timeless, nameless city, hard-boiled Detective Eddie Argo (Stellan Skarsgård) and rookie Helen Westcott (Melissa George) are chasing a serial killer out to test Price’s theory on love. Kidnapping a pair of loved ones – twin brothers, say, or a mother and her child – this demented predator straps both up to electric chairs. One of the pair is tortured, and given a noxious choice: to stop the physical pain, just flick a switch. The catch? Your loved one fries. As Westcott posits during the investigation, “How much pain will it take before you kill someone you love?”

With its torture scenes and fearless approach to depictions of violence, comparison with the likes of Saw and Hostel are inevitable. “I can totally see why,” Shankland says. “I don’t resent the comparison at all, I get it. The minute you see anyone tied up in a chair, having nasty things done to them, you can’t not think of Hostel. But I felt that we were up to something else.” Skarsgård echoes his director’s sentiments. “Early on in WAZ we had the discussion that it was essential that it be more frightening than gory,” he reveals. “That was the ambition – to not hesitate in showing terrible things, but not letting people escape the reality of the thing by being too much into special effects.”

So, is this the most violent movie ever made? “I think that would be so cool, that I could have a T-shirt saying, ‘I made the most violent film ever made’,” Shankland deadpans. “I think probably it feels more violent than it looks. What I hope is it’s as much about violence as it’s offering it up for entertainment’s sake. It hopefully gets into the emotion and psychology of violence.”

SELMA BLAIR Q & A

WAZ has some pretty horrific imagery. Where’s the line between exploitation and justifiable depictions of violence?
Oh God, I think to each his own. I don’t know if I even believe in exploitation. Someone’s putting something on the screen for some reason – if it’s gore just for gore’s sake, or just to show how soft our bodies are and how easily they can be mutilated. That all is for the end of some type of storytelling. I just don’t like to watch it, and I don’t like to be a part of it [laughs]. But then, there I am! But I liked the story because it was a story of love and redemption to me. It wasn’t a story about the gore.

How did you find shooting the rape scene?
That was a difficult day ‘cos I’m naked and somebody’s actually, you know, putting a bottle between my legs. I’m like, ‘You don’t actually need to put that broken bottle between my legs, you can pretend you are.’ That was the closest we got to for real gore. That was a bit tough, but Tom [Shankland] was amazing and shot it really quickly. I really trust Tom, I hope I get to work with him again.

You’ve just finished shooting Hellboy 2 haven’t you?
Yeah I just finished. It was sensational, I mean really sensational. It was a gruelling shoot. Guillermo’s such a perfectionist, he’s such an amazing creative genius – I don’t use that word for people, but I think he’s just above and beyond, and a great storyteller. It was 3 months of night shoots and 6 months of shooting in Hungary. The movie is gonna be amazing. I’m positive it’s just gonna blow people away. I know that a Hellboy 3 is being talked about. And if Guillermo’s doing it I’d be there in a second.