Following Ridley Scott's bold decision to hire veteran actor Christopher Plummer to replace embattled Kevin Spacey as J. Paul Getty in All the Money in the World, the next question is how the director will be able to complete the film in time for its Dec. 22 release by Sony's TriStar. 

While the studio says it is committed to hitting the release date for the film, which tells the story of the 1973 kidnapping of Getty's grandson, finishing on time could be a challenge — although not one beyond the skill set of a veteran director such as Scott. The filmmaker himself made the decision to erase Spacey, who has become toxic in wake of a series of sexual assault allegations, and Scott will be footing the bill along with production company Imperative Entertainment, according to insiders.

The techniques that Scott decides to use to replace Spacey with Plummer could ultimately depend on the complexity, logistics and number of the scenes involved. Spacey, whose supporting role is a critical one, shot a total of eight days and many of his scenes reportedly featured him alone. Plummer, The Hollywood Reporter has learned, is expected to be brought in for 10 shooting days. Mark Wahlberg and Michelle Williams, who star in the film as J. Paul Getty's lawyer and daughter-in-law, are also expected to return, which would allow Scott to stage full-fledged reshoots.

But as seen in the trailer, Spacey shot a least one scene where Getty is visiting a desert country and another where he confronts a large group of journalists — and those could be difficult to restage quickly. The movie itself shot in various locations, including Jordan, Italy and the U.K., according to IMDb.

So while Scott may reshoot some of the more intimate scenes in full, it's possible he could also resort to visual effects to reproduce others. For instance, Plummer could be placed in various locations by filming him against a bluescreen and then digitally inserting him into far-flung locales, a method that isn't uncommon.

It's also possible that some of the original footage could be used if Scott employs techniques such as compositing, stitching or reframing. For instance, if there's a two-shot of Williams and Spacey, it could be possible to reframe it to create a close-up of Williams — removing Spacey from the shot but keeping the same take of Williams' performance.

Another option is the delicate technique of head replacement, digitally grafting Plummer's head onto Spacey's body — possibly also using digital techniques on the body as well. Scott knows head replacement well. In fact, he may have been the first to have used an earlier version of the method when actor Oliver Reed suffered a fatal heart attack during filming of the director's 2000 film Gladiator. Footage from outtakes was used to create a sort of digital mask that was added to shots of a body double.

Head replacement has also been used for other purposes. It was employed to composite Natalie Portman’s face onto the performance of a professional ballerina in Darren Aronofsky’s 2010 film Black Swan. In another instance, a skilled pianist tickled the ivories in 2013’s Behind the Candelabra. His head was then replaced digitally with that of Michael Douglas, who played the role of Liberace in the HBO film.

VFX supervisor John Nelson (who also happens to be an Oscar winner for the VFX in Gladiator) used digital head replacement in Blade Runner 2049, which Scott executive produced. In that case, the script called for actress Sean Young as she appeared as Rachael in the 1982 original Blade Runner. To create a new scene with Rachael, a body double (Loren Peta) played the role on set with the other actors and then the VFX team replaced her head with a digital rendition of Rachael. Nelson also made digital adjustments to Rachael's body, as Nelson explained in a prior THR interview: “[Loren Peta] is an athlete, so her shoulders were a little bit broader than Sean’s at 19, so we took the body and scaled it down a little."

The Blade Runner 2049 work was accomplished at VFX house MPC, which is also providing VFX on All the Money in the World.