While Guillermo del Toro’s Pacific Rim didn’t exactly set the domestic box office on fire, its $400+ million worldwide earning made a sequel a strong possibility for Legendary Pictures. As such, del Toro recently revealed that he and screenwriter Zak Penn have been working in secret on a script for a sequel, though he stresses that the studio has yet to formally agree to put it into production. Dispelling rumors that the follow-up film to the mega-mecha feature will actually be a prequel, del Toro said that this picture would follow the events of the first. Also, the current version of the script includes Raleigh Becket and Mako Mori, played by Charlie Hunnam and Rinko Kikuchi in the first film. Hit the jump for more from del Toro himself.

While doing promotional tours for his FX horror series The Strain, del Toro talked to Buzzfeed about his surprising progress on the Pacific Rim 2 script:

“I’m working very, very hard with Zak Penn. We’ve been working for a few months now in secret. We found a way to twist it around. Travis Beacham [co-writer of the first film, now working on Fox’s Hieroglyph] was involved in the storyline and now I’m writing with Zak because Travis has become a TV mogul.”

Penn has a Jekyll-and-Hyde screenwriting career as he’s worked on scripts for X-Men 2, The Incredible Hulk, and The Avengers, but also Inspector Gadget, Elektra, and X-Men: The Last Stand. There’s no telling which version of Penn we’ll get on this script, but what we do know is that it won’t be a prequel story:

“Some people were wondering if we were going to do the prequel. I was never interested in doing that first wave of invasion. I’m going for very new, very crazy ideas on the second one, which are very different from the first one — but you will get really great spectacle.”

For those of you wondering whether or not del Toro will be back at the helm, Legendary’s CEO Thomas Tull commented on that fact recently with I Am Rogue:

On another subject, there’s a rumor that Legendary is working on a Pacific Rim 2. Can you confirm or deny that? Tull: Here’s the deal. We’re very close with Guillermo. He’s doing Crimson Peak for us right now. With the amount of money that we did on Pacific Rim, over $400 million, it didn’t quite hit our expectations, but it did better than a lot of other films. If there’s another great story to tell with Guillermo then we’re all over it because we think it’s really hard to create one of these things from scratch. The movie did really well on home video and merchandise, and it certainly has a big international following. We’re not just going to do Pacific Rim 2 just to do it. Right now we’re talking to Guillermo del Toro. If we can crack the story, we all think it’s great, and it’s him at the helm, then fantastic. But right now there’s nothing going on officially to proclaim.

For fans of Pacific Rim, myself included, this all bodes well for another installment of the robot-vs-monsters movie; as long as they don’t open against Grown Ups 3.