The Wolf in Sheep's Clothing

Once upon a time a Wolf resolved to disguise his nature by his habit, that so he might get food without stint. Encased in the skin of a sheep, he pastured with the flock, beguiling the shepherd by his artifice. In the evening he was shut up by the shepherd in the fold; the gate was closed, and the entrance made thoroughly secure. The shepherd coming into the fold during the night to provide food for the morrow, caught up the Wolf, instead of a sheep, and killed him with his knife in the fold.

Harm seek, harm find.