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