Mystery of the disappearing beets

(I meant to post about this last week, but I forgot.)

We've grown beets for years, primarily for the greens, which add a nice, somewhat bitter, accent to salads. Some years they don't do very well, but this year they came along fine (unlike, say, the lettuce). Not too long ago, jwg picked some and put them in the salad. Then last week I went out to get some to add to the salad I was making, and...

They weren't there. Well, there was one tiny beet plant. But apart from that, there was not a trace; no sign that any plants had ever been there. There were a few quadruped footprints (cat or dog, I think -- too big to be squirrel), but the ground didn't look dug up, and when I did a little scrabbling around under the surface, I found no trace of roots, either. It's rather as if someone had stolen the plants and done their best to hide any traces, which seems vanishingly unlikely.

I don't suppose we'll ever learn what happened.