Suddenly, a hand darted out of the darkness!
Suddenly, all the lamps went out.
Suddenly, he dropped his sword and ran.
Suddenly, the reader is warned that something sudden is coming!
Why do we warn them? What is the purpose of the one-word red flag?
Except in cases where we want our readers to know that a possibly casual event was sudden (He suddenly snatched up a handful of paper-mache), the “suddenly” warning defies the very idea of suddenness.
If your hero is to have no warning that her foe is about to drop his blade and scarper, the lamps are about to go out, and a hand is about to dart at her from the darkness, why should your reader?
Yes, it might take some work to smooth the prose over without suddenly‘s aid, but hey– good writing takes work.
What do you reckon? Does suddenly give a subtly lame edge to riveting action?