Matthew McConaghey, who will play a leading role in Christopher Nolan's Interstellar, is helping the director keep the project under wraps.
In an interview with MTV, the actor said that he hasn't even told his wife, Camila Alves, the details, simply saying: "I mean, [Interstellar's] a much more story-driven picture."
Based on a revised script by Christopher's brother, Jonathan, the story follows "a heroic interstellar voyage to the farthest borders of our scientific understanding".
Speaking about director Nolan, McConaghey said: "He knows what he wants.
"He knows everything about what's happening on a film set, and what everybody's doing."
Interstellar is Nolan's first film since wrapping the Batman Trilogy and will co-star Anne Hathaway, Jessica Chastain, Matt Damon, Michael Caine and Casey Affleck.