From Longman Dictionary of Contemporary Englishcloak-and-daggerˌcloak-and-ˈdagger adjective [usually before noun] SECRETvery secret and mysterious, and usually involving the work of spies a cloak-and-dagger operation
Examples from the Corpus
cloak-and-dagger• His enthusiasm for the cloak-and-dagger business of detection seemed to have waned.• He was arrested after a cloak-and-dagger operation involving the CIA and MI6. 