Guardians of the Galaxy was definitely a surprise hit for Marvel, with many commentators believing it to be their first commercial flop.

Of course, it wasn't and became a huge hit for Marvel and confirmed that if a reasonably original idea was put forward, audiences would go for it. Sure enough, a sequel was put into production and reports are seeping out from the set as to what's going. We've rounded up and confirmed as best we can all the rumours from the set and put forward a few theories of our own.

Check it out.

SO WHAT'S IT ABOUT?

Exact details are sketchy, but the official synopsis released a couple of days ago have it that Star-Lord (Chris Pratt) is continuing the search for his father, who we believe is played by Kurt Russell. Chris Pratt said that he's read the full script and that it made him cry, especially now that he's a father himself. Tommy Flanagan from Sons Of Anarchy has been cast and will reportedly play a Ravager who's out to collect the bounty on Rocket Raccoon (Bradley Cooper) whilst the sisterly relationship between Zoe Saldana and Karen Gillan's characters will be more heavily explored. As to who the villain is and what the overarching plot is, we've no idea. There's been some rumours of a living planet, but sources say Marvel nixed that idea as being way too weird.

WHO'S BEEN CAST?

The cast, in broad terms, are all returning. Chris Pratt, Dave Bautista, Zoe Saldana, Bradley Cooper, Vin Diesel and Michael Rooker are all returning. However, Glenn Close won't be back nor will Josh Brolin or his character, Thanos. Pom Klementieff has also been cast as Mantis whilst Kurt Russell has been confirmed as a cast member. It's been heavily rumoured - although not officially confirmed - that Kurt Russell will be playing Star-Lord's father. It was understood that Matthew McConaughey was to be cast in that role but then later passed. Comedian Steve Agee has been confirmed as having a small cameo role and, believe it or not, David Bowie was due to be approached to appear in a cameo before he sadly passed.

The big, BIG rumour circulating regarding the cast is that Al Pacino is in final negotiations to star as The Grandmaster, an Elder of the Universe who's connected to the story somehow. Gunn's initial treatment had it that Pacino would be the voice of Ego - a giant living planet, however Disney knocked it back and called it too risky. Again, there's been nothing officially confirmed other than whispers and rumours, however Gunn has said that he specifically wants to work with Al Pacino at some stage. It's not the craziest thing in the world, either. Marvel has a long history of getting high-profile, well-known actors in for stuff. Robert Redford in Captain America: The Winter Soldier, Michael Douglas in for Ant-Man and the aforementioned Glenn Close for Guardians of the Galaxy. You even had Jeff Bridges turn up in the first Iron Man.

WILL IT BE CONNECTED TO OTHER MARVEL MOVIES?

No, definitely not. James Gunn has managed to keep Guardians of the Galaxy fairly separate from the larger Marvel Cinematic Universe and plans on keeping it that way. As he mentioned in a recent interview, there'll be very little or no mention at all of Infinity Stones or Thanos in the sequel, instead focusing on ploughing its own furrow than crowbarring in references to Iron Man or The Incredible Hulk. That's a very smart move by Gunn. Guardians of the Galaxy is far too weird and closer to '80s sci-fi than anything in the current Marvel Cinematic Universe. Not only that, if what we're hearing about Civil War is correct, they're going in a much more darker, realistic tone. Guardians of the Galaxy is none of those things so why force it to be?

WHAT ABOUT THE SOUNDTRACK? WILL IT BE THE SAME '70s THEME AS THE FIRST ONE?

Yes. If you remember from the end of the first one, Star-Lord found a tape marked Awesome Mix-Tape Vol. 2 that will most likely form the basis of the soundtrack this time around. The time period that songs can be pulled from, as far as we know, would be up as far as 1988. You're talking Kenny Loggins, Michael McDonald, Duran Duran, any number of absolute classic bangers in the mix. There's been next to no word on what'll feature on the soundtrack, however during his tribute to David Bowie, James Gunn mentioned that he was the only artist to feature on both soundtracks.

WHEN IT'S GOING TO BE RELEASED?

Guardians of the Galaxy is due for release here in Ireland and the UK on April 28th, 2017.