see under wraps.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use keep under wraps in a sentence
Especially with casting, those things are hard to keep under wraps.The Leaner, Meaner Season 2 of ‘Marvel’s Agents of S.H.I.E.L.D.’ | Jason Lynch | September 22, 2014 | THE DAILY BEAST