The barn owl wears a valentine for a face, but he never sends it - he brings it. And like all small creatures of the night, the harvest mouse knows well its message: BE MINE. The owl-mouse affair has been going on for so long that it is a classic example of the enforcement of nature's unrepealable law that some must die in order that others may live. Is there a villain in the piece? Sure. The barn owl is a killer, say we who constantly strive to build a better mousetrap.