Here's the story behind Blade Runner 2049's most spectacular, spoiler-y cameo

WARNING: Spoilers for Blade Runner 2049 ahead. Do not scroll further if you wish to keep the surprise.

Blade Runner 2049, like its predecessor, is a visual splendor. And while plenty of scenes used big, neon lights and sweeping vistas to impress, it was a much quieter moment that made many audience members' jaws drop: the appearance of Rachael, looking exactly as she did 35 years ago.

So was this a body double or digital trickery? Turns out, a little bit of both. Visual effects supervisor John Nelson recently took Entertainment Weekly behind the scenes of the cameo, revealing the work involved in the Replicant's reappearance - as well as the level of secrecy surrounding her.

English actress Loren Peta stood in for actress Sean Young, who played Rachael in the original movie and worked on 2049 as an advisor. Dots on Peta's face helped Nelson lay a digital reconstruction of a young Rachael over the scene, and both Peta and Young were filmed with facial mo-cap while saying Rachael's lines. The end result is a ludicrously lifelike digital human, aping the behaviors of real-life actors.

"[Denis Villeneuve] got to direct [the scene] again when we did all the CG work," Nelson told EW. "All of those little moments of the mannerisms that we drilled into from the original movie, we incorporated those into the performance digitally." Nelson said he was particularly pleased with how well the hair turned out, as he feels that too often, digitally-crafted hair can look "too perfect."

Pretty fitting that in digitally crafting such a believable fake human, Nelson has built a proto-Replicant of his own.