Her mother nodded and went on. “The beef took only a few minutes to roast in the electronic oven. I remember my grandmother making so much of a pressure cooker. She probably would never have believed there would be an oven of the future that cooked in even less time than the pressure cooker and without any heat whatsoever.”

When the main course of the meal was over and apple pie was brought in, the children were sure this was the surprise Mrs. Kenton had promised. She said the supply boat had brought the fresh apples with the meat. But even the treat of apple pie was not the special surprise.

When supper was over Mrs. Kenton conducted the children into the living room and had them gather around a recording machine owned by their father. Mrs. Kenton set a spool of wire rotating and told them to listen.

“Hello, kids!” came a voice.

“Father!” Jill exclaimed.

They listened to a message addressed especially to them. When it was over, Mrs. Kenton explained that their father had called by remote broadcast from his distant work during the day. Then he had had her make a special wire recording for them so that they could hear it later. Mrs. Kenton told them this was the surprise. The children admitted that this was an even greater one than the beef and the apple pie.

“I thought Father sounded sort of sad or disappointed,” Jill commented.

“You were right, dear,” Mrs. Kenton replied. “Their work hasn’t gone along as well as they expected. They had a small landslide that buried the best of their diggings, which will take larger machinery than they’ve got to unearth. On top of that, the tracks they thought would prove to be a clue to the disappearing Martians aren’t human at all but belong to a group of animals they have already classified.”

“Gee!” Ted murmured sympathetically, remembering how enthusiastic his father had been before he had left. Now the greatest mystery on Mars—that of the disappearing Martians—was just as baffling as before.

“Because of this,” Mrs. Kenton said, “they’re ending the expedition ahead of time and coming home.”