Barry Docks is no place to be in winter. As if to confirm this I'm handed a call sheet for the day's filming as I travel along the Ffordd y Mileniwm from Cardiff station: "Dry with some sunshine" it states under the title "Daily Weather". "Feeling much colder with an easterly wind," it adds by way of detail.
David Schwimmer is the first person who comes into view as the car pulls up at the old seaside resort on the south coast of Wales. It's not very resort-like today. Seagulls screech, the sky is grey and the fairground rides have packed up for winter.
Schwimmer seems to be managing the temperatures better than me; living in New York, minus 4C is a cinch to him. "It is pretty cold, though," he offers cheerily. I find myself asking what on earth would induce a man to leave frosty and brilliant New York for this strange corner of the world in January. "I love dark comedies," he responds. "And I heard Simon Pegg was involved. It was a no-brainer. Let's just have a blast, I thought."
Big Nothing is about a man who dreams of doing something fabulous but fails and, in an effort to feed his family, decides to pull a scam to make a quick buck; it all goes staggeringly wrong. Entertainingly wrong, I discover when I open the script, having seated myself on the catering bus - the only warm place on set.
The idea that a film could demand a pairing of these two actors, so completely different in their humour and style - well, it's odd. "I was looking for two very different people," the French writer and director Jean-Baptiste Andrea tells me. "They have such different comedy skills. They are so culturally different and they look so different. All the great comic duos have been physically different."
These two really are different: the one all sweetly goofy, the other so cerebral and wry, so British, so ginger. "David's a lot less goofy in this," reflects Pegg. He's just finished shooting the scene where he finds that Schwimmer's character, Charlie, has accidentally killed the Reverend (who deals in porn and whom they were trying to bribe), and now they have to work out how to dispose of the body. The plot is convoluted and farcical; needless to say, one accidental death leads to another and by the end of the movie, well, there aren't many people alive. It's one of the bravest things about the film - the ease with which its scriptwriter discards his characters; Muriel Spark would have been impressed.
"The script is based on me," explains Andrea, who has directed one feature before this, the horror movie Dead End. "I was getting very frustrated with writing scripts and not having money to finance them so I decided to write a cunning story about a plan to pull off a robbery. You can't get away with something like that, there's always a price to pay. And I liked the idea of an honest guy, frustrated, deciding to do something wrong. And he pays for it."
Andrea has a cunning take on this sorry Everyman struggle that sits somewhere between Coen brothers and heist thriller. "I am really bad at reading scripts but with this one I stayed up with till three in the morning," explains Pegg, by way of justifying why he is in Wales suffering from a streaming cold and already parted from his newly acquired wife. "And I loved the part of Gus. He's a chancer, not a criminal or a murderer. In many ways he's as tragic as Schwimmer's character Charlie. It's fun to play someone so different to yourself. I could never carry off that sort of thing. Even if I was desperate I couldn't do it. I wouldn't have the balls to blackmail anybody."
Securing Pegg was the key to US financing. The success of Shaun of the Dead has meant that the 36 year-old writer/actor from Gloucester is big currency; he smiles at the unlikeliness of it. "I'm having a ball. And this, it's just a holiday, isn't it?"
A holiday? In Wales? With an easterly wind and a temperature of minus 4C? "A holiday is when I haven't written it. I haven't got any creative involvement. I just have to please the director. It's an utter release, it's just not my problem. And I felt like I hadn't acted in ages. I felt like I was atrophying because that's what I really love doing. I love writing but it's 51 per cent acting that I enjoy. So I said to Edgar Wright, who I write with: 'I'm going off to do some films now.'"
One after another at the moment. Mission: Impossible III and a film directed by Gwyneth Paltrow's brother, Jake, The Good Night, have preceded this one; and now Schwimmer is back in London directing Pegg in a new movie, Run, Fat Boy, Run, his directorial debut. "From the first scene that Simon and I shot, it felt that we just naturally clicked, like salt and pepper," Schwimmer offers poetically. The salt and pepper quite visibly revel in each other's company. I'm not surprised that they've gone on to make another movie together, nor that this time Schwimmer is directing it. It's the making of a film, how it all comes together, that excites him.
"Did you see that scene? Did you see what was involved?" he asks me excitedly. "For Simon's close-up there was the guy moving the camera on the dolly track, the director of photography, the focus puller, the boom operator, I'm off camera and I have to lean in and cheat my look for Simon, and I have to keep adjusting my body so I don't block his light. There were so many things to think about, everyone was working together to do one thing, which is to make the best performance on camera for the audience. It's really about the process for me."
But Big Nothing is not just a two-man show: there's a young girl who bravely fits into this tight-knit relationship, the Starter For Ten actress Alice Eve, who plays Josie, the most ruthless and possibly the only capable one of the pack. The Hungarian producer Andras Hamori shows me some of the rushes of her performance and she's terrific. Feisty and forceful, she also manages the American accent effortlessly.
"It's a hard one," says Pegg, who has a voice coach with him at all times, whispering in his ear after each take to advise whether he has got it right or wrong. "An American accent is one of those accents that everyone thinks they can do and everybody kind of can do a version of it but the specifics of it are very precise."
I'm curious to see how this bizarre combination of elements will come together. But judging by what is playing out on set and page before me, this is a gutsy effort.
'Big Nothing' opens on Friday