
"a furtive manner" "a sneak attack" "stealthy footsteps" "a surreptitious glance at his watch"
"clandestine intelligence operations" "cloak-and-dagger activities behind enemy lines" "hole-and-corner intrigue" "secret missions" "a secret agent" "secret sales of arms" "surreptitious mobilization of troops" "an undercover investigation" "underground resistance"