It was late 2018 and the makers of El Camino had just 36 hours with Bryan Cranston. Thirty-six hours in which to transport, make up and film Breaking Bad’s unforgettable antihero, Walter White, for his appearance in their then-secret movie.

Breaking Bad creator Vince Gilligan had written El Camino, a movie follow-up to his groundbreaking AMC show, clandestinely, and he intended to shoot the film under cover as well, relying on the discretion of his cast and crew at work in Albuquerque, New Mexico.

"We didn't want it ruined for the fans," says Gilligan, who also directed the film, which opened in theaters and premiered on Netflix Oct. 11. "Constitutionally, I don't want the things I look forward to spoiled. If there's a movie I'm looking forward to, I don't want to know jack squat about it before I'm sitting down in the theaters and the lights go down."

Among the headaches for Gilligan’s producers, Melissa Bernstein and Diane Mercer, engaged in this stealth mission was executing a key flashback scene with Walter White and Aaron Paul’s Jesse Pinkman in a diner. At the time, Cranston was appearing in eight performances a week of Network on Broadway, with Mondays off. Their plan was to fly Cranston out Sunday night after his show, shoot all day Monday and in the morning on Tuesday and wrap in time to get Cranston back to New York for his Tuesday night performance.

For the five seasons of Breaking Bad, Cranston had shaved his head to portray Walter, who suffers from cancer, creating an immediately identifiable silhouette that would eventually appear on T-shirts, stickers and mugs. But in late 2018, Cranston had a full head of hair to play news anchor Howard Beale in the Broadway show, and couldn’t shave it. To recreate Walter’s pate, a crewmember had flown to New York ahead of time to fit Cranston for a bald cap. It was, the filmmakers believed, the greatest bald cap of all time, but they were soon to learn it wouldn’t work.

First came the task of getting Cranston into town incognito. Breaking Bad and the city of Albuquerque are so indelibly intertwined that producers figured if Cranston so much as stepped foot in the Albuquerque airport, the jig would be up — everyone would know why Walter White had come home. They were also worried about the uncertainty of commercial air travel, which could derail their precisely timed shooting schedule for the scene. So the El Camino producers snuck Cranston out of New York with the help of a loaned private jet.

Because of Cranston’s limited time, they couldn’t take him to a remote spot, but had to shoot at a location in the middle of a busy intersection right in town. While filming at the diner, they blocked the set from view using screens and vehicles. One especially distinctive vehicle was parked outside: the beaten up Fleetwood Bounder that served as Walter and Jesse’s mobile meth lab. When passersby saw the distinctive RV outside the diner, there was a plausible explanation Gilligan and his crew hoped they’d believe: a local business had a replica vehicle that they used to give Breaking Bad-themed tours. (The ruse worked. On that shooting day, the tour bus operator’s phone started ringing off the hook with passersby asking questions).

El Camino centers on Jesse’s story, which meant that, after years as Cranston’s wingman, Paul had the first name on the call sheet. It was an unfamiliar feeling for the younger actor, who was otherwise surrounded by much of the same cast and crew with whom he’d shot five memorable seasons. "Bryan is an incredible leader, and we all learned so much from that beautiful man," says Paul. "Obviously he's my mentor, one of my dearest, dearest friends. The only strange thing about it was not having him around." On the day of the diner shoot, the duo were blissfully, if briefly, reunited.

For the crew, however, there were other, more prosaic concerns. The painstakingly made bald cap could not reproduce one of the most famous skulls in television history. Cranston’s hair was stuffed under it, so the silhouette was off. It was a problem the crew soon realized they would have to fix digitally, and as a result, nearly every shot in the diner scene is a VFX shot.

Gilligan was, however, able to achieve his key goal of keeping the existence of the movie—and the legend Walter White’s return to his hometown a secret. "I give all credit to our producers," Gilligan says. "I don't want to brag too much about all the great work they did, because someone's going to read this and say, 'I'm going to go hack this thing right now.' And then who knows?"