LOS ANGELES, April 23 (Reuters) - "Avengers: Infinity War" boasts more than 20 superheroes and expects to storm the box office, but even its A-list cast don't know quite what to expect when the film gets its world premiere on Monday night
Secrecy was key during filming on the Walt Disney Co. movie, which brings together almost every comic-book hero in Marvel's cinematic universe for an all-out battle with supervillain Thanos.
Most of the actors were given scripts for only the scenes they were filming, or given complete scripts that turned out to be fake, in order to prevent spoilers - particularly which characters may get killed off - from leaking out.
The cast will not see the finished product until the world premiere in Los Angeles on Monday night.
"I kind of like that," said Benedict Cumberbatch, who plays Dr. Strange. "I like that we'll be sitting in our own audience ... it's just going to be a thrill to watch it for the first time. I'm genuinely really, really excited."
With outsize heroes, including Captain America, Spider-Man, Iron Man, Black Widow, Black Panther and the Guardians of the Galaxy, comes massive fan appeal.
Analysts say the film could come close to, or even break, the $248 million North American box-office opening set in 2015 by "Star Wars: The Force Awakens," also from Disney.
Barton Crockett, media industry analyst at B. Riley FBR, predicted a $238 million debut for the film, which would make it the biggest opening this year.
The narrative seeds of "Infinity War" have been scattered through the Marvel cinematic universe franchise of crossover characters and plots since 2008's "Iron-Man."
"The theory that Marvel had when they started to make movies was that these movies would be promotional platforms for each other, stories that would continue to pull people along,” Crockett said.
"Infinity War," directed by brothers Joe and Anthony Russo, sees despot Thanos (Josh Brolin) fight the Avengers and their allies for all six of the legendary Infinity Stones that give the user specific powers to manipulate other people, objects or forms of energy.
"Thanos is a very interesting character because his agenda is to save the universe by destroying the universe," said Tom Holland, who plays Spider-Man. "It's something we haven't seen before and a lot of the movie is seen through his eyes."
Speculation has been rife about which characters may die but the directors declined to give details.
"Avengers: Infinity War" starts its international rollout on Wednesday and arrives in U.S. movie theaters on Friday. (Additional reporting by Lisa Richwine; Editing by Cynthia Osterman)