It's the wail of a lost spirit, loosed temporarily from the horrors of purgatory.

It's sent as a warning to repent you of your sins, and it's howling because it hates to go back.

What you going to do about it ?" He made his own intention plain beyond any possibility of misunderstanding.

He lay down and pulled the blanket over his shoulders, cuddled his pillow under his head, and disposed himself to sleep.
The moon climbed higher, and sent silvery splinters of light quivering down among the trees.

A frog crawled out upon a great lily--pad and croaked dismally.
Again came the wailing cry, nearer than before, more subdued, and for that reason more eerily mournful.