undercover
underground
SMART Vocabulary: related words and phrases
Plotting & trapping
be in league with someoneidiom
cahoots
catch someone out
chemtrail
chicanery
conspiracy theorist
conspiracy theory
conspirator
conspire
entrap
insinuate
outplot
plotter
ploy
pretext
pretextual
put-up job
sting
what's your game?idiom
wheeze
cloak-and-dagger | American Dictionary
cloak-and-dagger
adjective[ not gradable ]
us/ˈkloʊk·ənˈdæɡ·ər/
involving mystery and secrecy:
a cloak-and-dagger spy mission