under wraps

1. Concealed or secret, as in The design for the new plant is under wraps. This idiom frequently is put as keep under wraps, meaning “keep secret,” as in Let's keep this theory under wraps until we've tested it sufficiently. It alludes to covering something completely by wrapping it up. [1930s]

Example Sentences

Even the program handed out to theatergoers keeps one character’s identity under wraps.

From Los Angeles Times

Teasing the Peaky Blinders film, which has been written by the show's creator Steven Knight, Murphy said: "I think it's better to keep it under wraps, keep it a surprise."

From BBC

Story and production details for the untitled “Summer I Turned Pretty” movie are under wraps, as is the release date.

From Los Angeles Times

Although story details for the movie are still under wraps, the studio said it would be the final chapter of Belly's journey.

From BBC

Patel said the Biden administration was keeping the address book under wraps to protect individuals who were named in the files.

From Salon