“Did that stop the sickness?”

She nodded. “Immediately. The hospitals emptied out in no time at all, and there hasn’t been a case of that disease since then.”

“Is that all?” I asked.

“Hardly. The trouble didn’t start until after we were all wearing the collars.” She took my hand and guided it along her collar to the back of her neck, where I felt a tiny joint in the metal.

“What’s that?” I asked.

“That joint is the weapon those three hold over us at all times. These collars, you see, can be tightened at will by remote control—and my father’s three friends operate the controls!”

I whistled. “What a hideous kind of dictatorship! You mean—anyone who makes too much of the wrong kind of noise gets his collar tightened.”

“Exactly. As soon as the whole city was wearing the protective collars—the collars that we thought were our salvation—the Three called a public meeting, and announced that they were taking over the government. Mayor Coldridge stood up to protest such a high-handed move—”

“And suddenly felt his collar tightening around his neck!” I concluded. I could picture the scene vividly.

“It was terrible,” she said. “Right in the middle of his speech, he clutched at his throat, went red in the face, and sank to his knees. They let him up after a minute or so, and explained what they had done. Then they announced that anyone who protested against what they were doing would get similar treatment. We’ve been against them ever since.”

I stood up, almost overwhelmed with anger. I had come to the right place this time! Maybe giant Jupiter was something I needed to explore someday for my own peace of mind, but this mess on Callisto required immediate attention. I didn’t see how I was going to fight it, either, but I swore to myself that I wasn’t going to leave here until the last collar had been removed from a Callistan throat.