lurking

concealed and unsuspected

• “lurking dangers”
• “search for lurking ambiguities”

marked by quiet and caution and secrecy; taking pains to avoid being observed

• “a furtive manner”
• “a lurking prowler”
• “a sneak attack”
• “stealthy footsteps”
• “a surreptitious glance at his watch”
• “someone skulking in the shadows”