One the most surprising box office hits of 2018 so far has been Den of Thieves, and we have some exclusive story details on the upcoming sequel, Den of Thieves 2. The first movie - a 1990s-style cops-and-robbers morality tale - was in development for over a decade thanks to the bankruptcy of original studio Relativity Media, but finally released this past January and despite getting negative reviews from critics, made over double its budget back at the box office (which in Hollywood maths means a profit).

Still, it came as something of a surprise when a sequel was greenlit, with writer-director Christian Gudegast and star Gerard Butler set to return for more morally ambiguous cops and robbers. The first movie ended on a The Usual Suspects-style twist that certainly kept the door ajar, but it definitely didn't feel like Marvel-esque setup.

Related: Gerard Butler Talks Den of Thieves

Screen Rant recently sat down with Gudegast to discuss Den of Thieves and the development of its sequel for the original's home video release (on digital April 10, DVD/Blu-ray April 24), where we dug deep into what the plot of Den of Thieves 2 will be, where it will take Butler and an also-returning O'Shea Jackson Jr., and who may be joining them.

Like the first movie, which was inspired by a real life attempt to rob the Federal Reserve in Los Angeles, Den of Thieves 2 will be based on a true event - in this case the Antwerp diamond exchange heist of 2003 - with the two main surviving characters at the center of the story: original mastermind Donnie (Jackson) will be on the run with the former Pink Panther mafia after a diamond heist goes wrong, hunted by Interpol and Nick O'Brien (Butler), who's left his L.A. life and family troubles behind for Europe. The film will cover a bevy of European locales, from London (where the first film ended) to Belgium, Marseilles, the Cote d'Azur, and Montenegro, bringing with it an overall lighter tone to the gritty original.

The project is currently in the development, with the story fully mapped out and Gudegast ready to begin script work once the studio deal is sorted. Outside of the two returning stars, no other casting information is set, but the director wants to again gather a range of actors as well as potential fighters and footballers.

Our full interview with Gudegast will be online in later this month, but here are the exclusive details on Den of Thieves 2:

Did you ever think that it [the twist] would end up serving as a springboard into doing a sequel?

Initially not. That's all a function of studio filmmaking. Every studio wants a little mini-franchise if possible. Thankfully, thank god, we're all very fortunate that it did very well and now we're going to do a sequel which is great. But that wasn't initially the plan. That's just something that sort of you know as we were making it and we were feeling that the twist was working, and it setting up well for a sequel - if it performed, that we would do one. And it performed so... The sequel will be something that I have researched for years and years. I'm adapting a different story to make it a sequel about the Pink Panther mafia and the diamond thieves from Europe.

And what sort of stage of development is the sequel - congratulations on that by the way - what sort of stage is that in? If you've been developing the story for a while you must be further along than if you've just got a green light.

Correct. The whole story is done. It's not written, but the outline is completely finished. We're now just waiting for all the deals to be done with the producers the stars etc. And once that's all handled, I will write it. But it's all... the hard work is done. It's all structured, it's all outlined, I have the whole story. It's just a matter of putting pen to page.

And is that going to bring (should all the deals go through) Gerard and Donnie back together and have those two as cop/criminal - advance that relationship? Or when you say it's going adapt another story is it going to focus more on Gerard's character?

They're both going to be it. It's all going to be set in Europe. And it's going be about Big Nick hunting Donnie, who's involved in a diamond heist and he's teamed up with the former Pink Panther mafia, and it's about Nick hunting him along with... Nick is also going to be hunted by another group, I won't reveal right now. It's gonna, there'll be a few different kinds of twist in this one. It'll be hopefully very surprising.

So it's really sort of stepping beyond - I'm really glad it's set in Europe, I can't wait to see what you do with a different location given how much LA was in this one - but in terms of expanding the idea, where do you see Den of Thieves as a franchise? If you now had to define the "Den of Thieves franchise", what would say it is?

It is about... the A-plot is centered around or based on actual heists - this will be based on the Antwerp diamond exchange heist of 2003 - and it's about, on the character side, it's about the blurring of lines between the sides. And sort of an examination of all the people involved in this world and how they are much closer to in terms of their character and who they are. Your actions make almost the exact same person, and in this next one I think the hunters will become the hunted, and it's an examination of that.

And in terms of influences, this first movie obviously had shades of Heat and The Usual Suspects. Is there any specific movie you're honing in on as an influence for Den of Thieves 2?

Yes. Gomorrah, Suburra, Sexy Beast and Ronin. Those four.

So much more European then?

Yes, much more.

Can you say what cities you'll be visiting? Or is that not set yet?

Yeah, it is. It will briefly in London, it will be in Belgium, it will be in Marseilles, it will be in the Cote d'Azur, and it should be in Montenegro.

And so with the sequel... one of my concerns with the sequel after watching the movie is that you spend so much time building up these two gangs, these two sides - the criminals and the police - and you kill the majority of them in the finale, especially on the criminal side. In terms of building up that new team - you obviously got the Pink Panther side for the criminals - are you going to build up a new cop squad for Nick?

We are. We are. There are going European based, from Interpol, and a few of the old cops are going to come over from the united states, but they're going to be working with a whole new cast. We are very excited to cast a bunch of great European actors, and it's going to have a whole different sort of energy and vibe. It's going to be a very cool, sort of European gangster vibe.

I'm sure you can't talk about casting or anything but one thing that was really a cool sell for Den of Thieves was the cast - you have such an interesting set of actors on both side of the line. What sort of stars are you going for this time? Some up-and-comers, some unknowns - what sort of dynamic are you looking to create?

A combination. Some like known great European actors. Some up and coming young actors - European - and then like we did in the first Den we'll probably put in a few more fighters, maybe like Anthony Joshua, someone like that. And then maybe even some footballers.

OK, wow. So real mix and very authentic feel kind of thing?

Exactly.

Will you be going more into his past - because obviously, we had the family life in the first one - but his was said, but you left plenty of room for interpretation, which gave him a mysterious quality. Will you explore who is a bit more in the sequel?

A little. We will, a little bit. We'll different aspects of him, we will. But it's also going to be a little less... the tone of this next movie's going to be a little more fun because it's almost like he's escaping to Europe to get away from his wife's problems, so it's going to be a fun ride.

Interesting you mention the fun and the lightness. Because that was one thing that I thought worked really well - his relationship with the FBI and that antagonistic bro humor that they had. So that's going to be much more prominent this time around then?

Yes. Exactly right.

Next: O’Shea Jackson, Jr. Talks Den of Thieves

Den of Thieves is available on Digital from April 10 and Blu-ray/DVD from April 24.