Yes, Martha knew that frown, and it made her grin. She couldn't help it, because Hermione reminded her of one of the other times that she had told this story, to a listener who had a very similar reaction.

"Actually, it's against intergalactic law to hunt people on Earth. See, we're a class three planet, and we're not civilized enough to interact with. They think of us a bit like plankton, really. But they were hunting a plasmavore who had killed a princess."