Five mysterious creatures, evil, of course, descend upon the isolated town of Brinkley Springs to consume human souls. They can change their shape from crows to men. They've managed to put a type of force-field bubble over the place so the struggling survivors cannot escape. But what they did not count on was that they also trapped an ex-Amish magus, Levi Stoltzfus, who knows a way to stop them.
This was an enjoyable enough read, though this is the "Night of the Living Dead" scenario done yet again. And Keene has written a similar book, DARKNESS ON THE EDGE OF TOWN, which is far better.