On any list of best Black Mirror episodes to date, season fours USS Callister hovers near the top, with many fans and critics calling it their favorite of all time. Part Star Trek homage, part virtual-reality nightmare, part deliciously executed revenge scheme, USS Callister also made a mark with its special effects and standout performances. No wonder, then, its the first Black Mirror episode to get a sequelbut it wasnt always a smooth road to get there, something show creator Charlie Brooker spoke about in a new interview. With season seven, which includes the much-anticipated USS Callister: Into Infinity, arriving next week, Brooker talked to Deadline about how it all came together. Apparently, he considered turning the original story into either a limited TV series of its ownor a feature film, after the episode made such a splash after debuting in 2017. Of all the stories weve done this one ended as though we were setting it up for the sequel, Brooker told the trade. It went through various guises but in the end we made it feature length within the season. It took so long getting it togetherwe had the pandemic, writers strike and then had to get everyones schedules lined up, and that was its own Rubiks cube on a unicycle. Fans will recall the original episode starred Cristin Milioti and Jesse Plemonsbut Plemons villainous character, Robert Daly, died at the end. Aside from Plemons and another character played by Michaela Coel, though, everyone else is back: Milioti (Nanette Cole), Jimmi Simpson (Walton), Billy Magnussen (Valdack), Milanka Brooks (Elena, who somehow has her blue alien skin again?), Osy Ikhile (Nate), and Paul G. Raymond (Dudani).The digital clones of their human characters, according to a Netflix synopsis, are now stranded in an infinite virtual universe, fighting for survival against 30 million players. It seems likely well also catch up with their real-life counterparts, too, and maybe see whats happened with the Infinity game now that Robert Daly is no longer oozing his toxicity into its programming, or swiping DNA around the office. Black Mirror season seven hits Netflix April 10. Want more io9 news? Check out when to expect the latest Marvel, Star Wars, and Star Trek releases, whats next for the DC Universe on film and TV, and everything you need to know about the future of Doctor Who.