LOS ANGELES (CBSDFW.COM/AP) – Iron Man actor Robert Downey Jr. is joining the directors of “Avengers: Infinity War” in calling for movie fans to maintain secrecy.

The star tweeted “no spoilers please.” He signed it with #ThanosDemandsYour Silence. Thanos is the fictional Marvel Comics villain who will be portrayed by Josh Brolin in the movie.

Directors Joe and Anthony Russo went on Twitter to tell fans they would be screening a limited amount of footage prior to the film’s release on April 27. They say “only a handful of people know the film’s true plot.”

The filmmakers asked fans to maintain the same level of secrecy so that they don’t spoil it for others.

“Avengers: Infinity War” will be the 19th entry in the Marvel Cinematic Universe, the company’s world of connected films that began with “Iron Man” in 2008 and now includes movies like “Guardians of the Galaxy” and “Spider-Man: Homecoming.”

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)