A worried face, burdened with a hundred lives and vital secrets to preserve.

Where there had been one German soldier, twenty appeared to guard this vital secret.

"There is nothing in the book that says we have to throw away secrets vital to our national defense."

We're talking about basic data, not vital secrets that the city might reasonably want to hold tight.

Let him stumble on a vital secret, as it were.

But thanks to you the vital secret they needed is safe from them still, for as many centuries perhaps as.

"What vital secrets could a bunch of Soviet psychologists want to steal?"

"Are there any other obvious facts you'd care to point out as if they were vital military secrets?"

He couldn't run the risk that somehow vital secrets would fall into the wrong hands.

Whoever killed those five Home Guards has learned a vital secret.