Temporary Mystery

I'm frozen in the doorway.
He's dead.

Who's dead? How is he dead? Murdered? Where are they? Who is the main character?

When a book starts with action, the first sentence creates mystery. That's pretty much unavoidable. I have been bemoaning this problem while pointing out its inevitability.

But mystery can intrigue the reader to keep reading. That's good for the author, but I think readers also like an incentive to keep reading at the start, as opposed to forcing themselves to keep reading.

So there could be a good side to the unavoidable mystery in an action start, and in any case it's apparently tolerable to readers. That's why action starts can exist – the reader keeps reading to understand what's happening. If some authors deliberately prolong mystery, how bad can it be to have a little unavoidable mystery that is quickly cleared up?

Not Prolonging

In the above start, some of the mysteries are a basic part of the book and not answered until the end -- who is he, why was he killed, why is his body there? But the others are not – the action continues and information about setting is given or leaks out. I wasn't in a hurry to supply the missing information, but I wasn't deliberately withholding information, I wanted it to leak out.

I'm supposed to be here – Mrs. Andersen told me to get a top hat. The dead body is NOT supposed to be here.

There's a lot of character here – she's a rule follower, and she's not in charge. In fact, she was told to do something that is obviously an unskilled errand, and she calls her supervisor "Mrs.", suggesting she is not an adult.

I try really hard to see his chest move. It doesn't. His arms and legs are in an odd position, like someone dumped a dead body on the floor for me to find.
I should tell Mrs. Andersen! I back out of the storage room, slam the door shut, and run. I dash past Belle practicing her lines with the Beast, techies repainting a backdrop, and I dodge through some teacups and silverware doing their homework. Someone yells at me, annoyed, "Watch it, Screech."

If I had stopped to describe setting, I could have cleared up a lot of mysteries in a hurry – the main character is a 9th grade girl assisting the teacher on a play. Because I was maintaining action, the mysteries are filled in more slowly.

Actually, it takes 260 words to find out the main character is female. That's unfortunately slow. But I wasn't intentionally withholding the information, it just didn't come up naturally.

You can see as you read if the author is deliberately prolonging the mystery or not. But even with no prolonging, it takes time for things to come into focus. Meanwhile, hopefully the action is interesting.