LONGCROSS, U.K. — The drizzling skies and muddy ground are pure southwest England, but the ramshackle sci-fi frontier town I’m wandering through is meant to be somewhere at the edge of the universe.

Welcome to the middle of Knowhere, a favourite watering hole of the Guardians of the Galaxy. And, today, they are having fun.

Blasting into theatres Aug. 1, Guardians of the Galaxy is Marvel’s weirdest, riskiest movie to date: a massive special effects space opera based on obscure comic book heroes (including a walking tree and a talking raccoon) and directed by a guy best known for one low-budget comedy-horror.

But Marvel has faith, the cast and crew have faith, and on this mid-September day at Longcross Studios, about an hour southwest of central London, Guardians of the Galaxy star Chris Pratt is preaching to the choir.

“Let’s f---ing crank it up on this one!” bellows Pratt, decked out in the signature red leather jacket of Peter Quill, a.k.a. Star-Lord, an intergalactic rogue who’s sort of like Han Solo with the mind of a 14-year-old boy. “This s---’s gonna be a movie!”

Indeed it is. Guardians of the Galaxy will be the second-last film in Marvel’s Phase 2 continuum before next year’s The Avengers: Age of Ultron puts a bow on it. But unlike Iron Man, Thor and Captain America, Star-Lord and pals are far from household names.

Director and screenwriter James Gunn (Slither) says that’s part of the appeal. “When you make The Avengers, there are a lot more people who have an idea of what the movie should be,” says Gunn. “And with Guardians, it gives me a lot more freedom to reinvent them for this universe.”

On this day, I’m with a handful of journalists touring several of the massive Guardians of the Galaxy sets at Longcross Studios and nearby Shepperton Studios. Art director Thomas Brown leads us through the interior of Star-Lord’s ship, the Milano, decorated with relics from the ’80s: everything from Alf trading cards to a Rubik’s Cube, mementos of the decade that Peter Quill was abducted from Earth by space pirates.

A short walk away is the set of the Dark Aster, the massive spaceship belonging to Ronan the Accuser (Lee Pace), one of the Guardians’ major foes. Made primarily of plaster that looks like aged stone, the enormous and spartan 60 metre-long set took six months to design and four months to build.

And on the outdoor set of the frontier town on Knowhere, giant engines are suspended from chains hanging off dilapidated metal facades, while a rundown shop is selling a variety of vacuum-sealed bags of strange spices, plants and animal parts.

For today’s scenes, the Guardians — Peter Quill, Gamora (Zoe Saldana), Drax the Destroyer (ex-wrestler Dave Bautista) and the dynamic duo of Rocket Raccoon and Groot (the voices of Bradley Cooper and Vin Diesel) — have escaped prison and arrived here, at a bar packed with all shapes and colours of alien humanoids.

The scene is a dramatic shouting match between Rocket and Drax, with Gamora and Quill intervening to keep the peace while Groot watches from the sidelines. But because Rocket and Groot are CGI characters to be added in later, the rehearsals have actors in green bodysuits standing in for the characters. “Rocket” sits on the floor to give the proper eyeline for the two-foot-eight genetically altered critter, while “Groot” wears a mask atop a short pole attached to a headband, to give the actors an idea where to look when addressing the seven-foot-six tree-like alien.

“Keep calling me vermin, tough guy!” shouts Rocket to Drax, who is being physically restrained by Gamora.

Quill tries to settle them down, but Rocket is having none of it. “He called me vermin! She called me rodent!” seethes Rocket.

Drax has had enough: “We have travelled halfway across the quadrant, and Ronan is no closer to being dead!” he growls, before shouldering his way through the packed bar.

It’s intense stuff, but these guys are clearly enjoying themselves, and if there’s any concern that Guardians of the Galaxy is going to be too offbeat for mass consumption, no one is showing it. At all.

One way or another, this trip to the edge of the universe is going to be a memorable one.

CHRIS PRATT: 'STAR-LORD MORE MARTY MCFLY THAN TONY STARK

He’s been everything from a lovably hapless civil servant (Parks and Recreation) to a Navy SEAL (Zero Dark Thirty) to a wee plastic construction worker (The LEGO Movie). But to hear Chris Pratt tell it, he’s never had more fun than right now.

“Dude, it’s the most f---ing exciting thing I’ve ever done in my life!” says Pratt, taking a breather between scenes on the set of Marvel’s upcoming oddball space opera Guardians of the Galaxy.

Though he’ll also be starring in next year’s Jurassic World, Guardians of the Galaxy marks Pratt’s first real turn as an action hero, playing the spacefaring rogue Peter Quill, also known as Star-Lord.

And while Star-Lord exists in the same universe as the Avengers, “I think this character is more Marty McFly than he is Tony Stark,” Pratt says. “There’s a youth to him and a vibrance and a petulance. He’s like a kid.”

Pratt was on a long list of actors being considered for the part of Peter Quill, a roster that included everyone from Joseph Gordon-Levitt to Aaron Paul. “There are far more heroic badass actors out there than me, but (director James Gunn) hired me for a reason,” says Pratt. “I think it might have something to do with being able to do the comedy with a straight face.”

Now, he’s signed on for up to three Guardians movies, plus cameos in a couple other Marvel films. And, in a weird way, fate seemed to be on his side.

“I didn’t collect a lot of comic books, but there was one time I won $300 at bingo with my mom — we didn’t have a ton of money — and I just spent it all on comic books,” says Pratt. The books he bought? Batman, Wolverine, the Punisher... and Guardians of the Galaxy.

JAMES GUNN BRINGS SIGNATURE STYLE TO OFFBEAT SPACE OPERA

When director and screenwriter James Gunn turned in his first draft of Guardians of the Galaxy script, fellow filmmaker and Marvel go-to guy Joss Whedon (The Avengers) had just one complaint.

“Joss said, ‘I wish there was more James Gunn in this script,’ ” recalls Gunn, speaking from the set of the upcoming Marvel space opera, in theatres Aug. 1.

Marvel Studios president Kevin Feige agreed with Whedon’s assessment: the script needed more of Gunn’s uniquely weird perspective.

“And I was like, ‘It’s your funeral, let’s do it,’ ” says Gunn.

Judging from time spent on the film’s sets at England’s Shepperton and Longcross Studios, as well as the movie’s cheeky yet action-packed trailers, they hired the right Gunn. Still, Guardians of the Galaxy poses a risk for Marvel. Will audiences react to these relatively obscure comic book heroes the same way they did to the Avengers?

Gunn makes a good point: If the only people who went to see Iron Man were existing fans of the Iron Man comics, “that movie could have never made money,” he says. “You’re making the movie for the world.”

The world will need to wrap its head around characters like a man-child space rogue called Star-Lord (Chris Pratt), a green-skinned assassin named Gamora (Zoe Saldana) and the genetically and cybernetically enhanced varmint Rocket Raccoon (voiced by Bradley Cooper.)

“Yes there’s a talking raccoon at the middle, but with that talking raccoon, how could that creature really exist and who would he be?” Gunn says.

“There’s some dark humour, but there’s a lot of drama in the movie too. There’s just a whole lot of drama.”

JUST WHO ARE THE GUARDIANS OF THE GALAXY?

The who of the what now?

They might not have the same profile as the Avengers, X-Men or Justice League, but Marvel’s Guardians of the Galaxy have been exploring the cosmos in one form or another since 1969. The spacefaring super-squad has undergone several changes over the years, including a self-titled comic series in the early ’90s and a new line-up featured in a 2008 reintroduction of the intergalactic anti-heroes.

It’s this latter-day reboot of sorts — featuring Star-Lord, Rocket Raccoon, Quasar, Adam Warlock, Gamora, Drax the Destroyer and Groot — that forms the basis of the Guardians of the Galaxy movie.

While not every character featured in the comics will make the transition to the big screen, director and screenwriter James Gunn says his cinematic interpretation of the somewhat obscure heroes will be grounded in emotion, even as it explores the universe.

“People are going to be very surprised when they see the dramatic elements of this movie,” says Gunn. “There are very sad elements to this movie that they really haven’t gotten into with the rest of the Marvel films.”

Twitter: @stevetilley

steve.tilley@sunmedia.ca