cloak-and-dagger

Joe said politely: “I heard there was cloak-and-dagger stuff going on.”

You risked your life on cloak-and-dagger missions; let the shore-bound fancy dans do the drudgery.

It has been said of Time, earlier in these pages, the cloak-and-dagger sort he is, that stalks and pounces.

He climbed out, standing alongside the bed in his shorts, wondering at the Colonel's cloak-and-dagger approach.