Imagine a musical in which Cinderella’s prince cheats, Red Riding Hood and Rapunzel suffer horrible fates, and Jack (of the Beanstalk fame) nearly brings about the end of civilization: It’s not exactly traditional Disney fare.

Yet that’s what moviegoers can expect at Christmas: the Disney-produced “Into the Woods,” director Rob Marshall’s adaptation of the Tony Award-winning Stephen Sondheim musical that turns “happily ever after” into “be careful what you wish for.”

Meryl Streep, Johnny Depp, Emily Blunt, Anna Kendrick and Chris Pine lead the cast of the season’s most-anticipated musical — by a studio best-known for its sunny, animated fairy-tale characters dating back more than 70 years to “Snow White and the Seven Dwarfs.”

“It is a very un-Disney film,” says Blunt, who inhabits the critical role of the Baker’s Wife, the character that sets much of the plot in motion with her desire for a child. “It is very funny, very human. I think kids will enjoy it but there are very adult themes running through it.”

Marshall, who hit the jackpot when his “Pirates of the Caribbean: On Stranger Tides” (2011) made more than $1 billion worldwide box office for Disney, returns to the genre that placed him on the A-list when “Chicago” (2002) became the first musical in 34 years to win an Oscar for best picture.

“I was very keen on doing a Sondheim musical,” Marshall tells Variety. Back in the ’90s, he choreographed the Broadway revivals of Sondheim’s “Company” and “A Funny Thing Happened on the Way to the Forum,” and had spoken with the legendary theater composer about “Into the Woods” more than a decade ago.

“This is a fairy tale for the 21st century, for the children of today, who live in a much more unstable and complicated world than I did growing up,” says Marshall.

According to screenwriter (and original Broadway scenarist and director) James Lapine, Act I of “Into the Woods” is among the most licensed shows for school-age audiences, because of its upbeat ending.

But many omit the much darker Act II, which deals with the consequences of the characters’ often selfish acts. “The challenges were inherent, but the potential for brilliance was also there,” says Mitchell Leib, president of music for Walt Disney Studios.

Producer John DeLuca (in cap) and director Rob Marshall (center left) view rushes with actors James Corden and Emily Blunt. Producer John DeLuca (in cap) and director Rob Marshall (center left) view rushes with actors James Corden and Emily Blunt.

So Disney signed on, authorized a $50 million budget, and took the leap with a three-month shoot late last year in England. And because Marshall has a long history in American musical theater, the first thing he did was to involve both Sondheim and Lapine.

Sondheim buffs have been buzzing for months about what might have been trimmed (the original show ran about 2½ hours, the movie is about two) and whether the involvement of the family-friendly studio has resulted in a softening of the musical’s harsher realities.

“It’s all there,” Marshall insists. “It actually harkens back to the original Grimm fairy tales. This is very much a cautionary tale.” Although he also points out that, as he did with “Chicago” and “Nine,” “you have to reinvent to make it work for film.”

Sondheim, who is in New York working on a new show, was unavailable for this report. But according to his longtime collaborator Lapine, “it was a given that it would have to be edited down. We did a lot just to make it cinematic.”

Lapine worked with Marshall for months and together they made choices to “maintain the integrity” of the source material. “There are some changes, but they are in no way major,” he says. “It’s very true to the show.”

Final tweaks were still being made to the film in late October, so few have seen “Into the Woods” beyond those involved.

Sondheim has altered lyrics here and there, Marshall confirms.

“He loves film and understands that it’s a different medium. Both he and James were incredibly flexible.”

Unlike the much-talked-about “Les Miserables,” which was all sung live on set (causing considerable difficulty for the music team in post-production), “Into the Woods” was done the traditional way, by pre-recording the songs and then having the actors match their singing on the set.

Meryl Streep shot her “Witch’s Rap” live, according to the filmmakers. Meryl Streep shot her “Witch’s Rap” live, according to the filmmakers.

Marshall brought the cast together to rehearse for four full weeks in July 2013, before any of the songs were recorded. “Rob blocked out nearly every scene in a big soundstage, so everybody knew what they were going to be doing, to a pretty detailed level, for their shots,” says music producer/supervisor Michael Higham.

Sondheim vet Paul Gemignani, who conducted the original show, conducted a 53-piece orchestra at London’s Angel Recording Studios, and then the whole cast — by then thoroughly prepared — recorded their vocals separately. Higham says 93% to 94% of the studio recordings ended up in the film. “We got it bang-on with the (studio) performances. The rest ended up being a live vocal (on the set).”

This took much of August, and Sondheim was present, Marshall says, “to give thoughts and ideas to the actors.”

Inevitably, changes were necessary, Higham says: Tracey Ullman, as Jack’s mother, wanted to speed up the song’s tempo, requiring adjustments later.

And when they shot Streep’s “witches’ rap” during the long opening prologue, as she explains the curse on the Baker’s family, “Meryl did that live,” Higham says. “It was one of the most impressive things I’ve ever seen.”

Late this summer, Julian Kershaw conducted a 72-piece orchestra in about 40 minutes of underscore, all based on Sondheim’s original music.

One undeniable disappointment for the completists out there: Sondheim wrote a new song for the movie, “She’ll Be Back,” for Streep as the Witch. It was shot, but cut after an early preview. Marshall concedes the cut was “painful, especially a new Sondheim song which is so thrilling,” but that the film worked better without it. And “the first people to notice were Stephen and James.” (It will be on the DVD next year.)

In the final analysis, it’s a movie, not a stage show, Marshall is careful to remind. “You’re not aware of when the numbers begin and end,” he says. “It moves in and out of dialogue, between narrative and songs, seamlessly. It’s a different way to go, for sure, and expands what a Disney fairy tale can be.”