She tried disease. She tried floods and earthquakes. She tried mass starvation. None of it worked, so she plucked an asteroid out of space and sent it like a rock from a slingshot. Hell, one got rid of the dinosaurs, so how difficult could it be to get rid of the upright apes called man?

Answer. It wasn't.

One spaceship made it. Most of its crew didn't. Five hundred years is a long time in cryo-stasis.

And now they've come home, back to Earth, but she's put conditions on their return, and they're tough.