“Randy, wake up!”  
Ted was jostling his bedmate. Randy opened sleepy eyes. He seemed to be unaffected by the reduced air pressure in the room. Ted remembered that people vary in their reaction to this.
 
But when Ted told him of the danger, Randy bounced out of bed with no further prompting. Ted switched on a light, and just as he was reading the air-pressure gauge on the wall, he heard a shrill whistle in the house. It was the air alarm that had gone off automatically. Ted could see that the gauge read dangerously low.
 
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If he and Randy and the others did not get into space suits in a hurry they would suffer serious consequences, one of which could be an attack of the “bends.” At worst, they would lose consciousness and die of anoxia—oxygen starvation.
 
Even before Ted could leave the room to rouse his mother and sister, both were standing at the boys’ door.
 
“We’ve got to get on space suits right away!” Ted told them. “It looks like all the air pressure in the house is leaking out!”
 
They went immediately to the closet and began dragging out space dress in a mad flurry of fear. They pulled on the suits and helmets with haste and inflated the airtight outfits with fresh, pressurized oxygen from the small tanks on their backs.
 
“What do you think has happened to the air drum in the basement?” Mrs. Kenton asked her son over her helmet radio.
 
“I don’t know, but Randy and I can go down there and see,” Ted answered.
 
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The boys went downstairs, made a light, and walked over to the giant metal tank recessed in one of the walls. Checking the gauges on the tank, Ted turned to Randy with a frown.
 
“There’s nothing wrong with this,” Ted said.
 
“Then where is the trouble?” Randy asked.
 
(uncaptioned)
“There must be a leak somewhere in the house,” Ted said. “We’ve got to find out.”
 
The boys went upstairs, and Ted told his mother and sister that all of them should spread out and search the entire house for a leak. There were emergency sealers on hand to plug such a leak when it was found. The sealers were only temporary, but they would last until a full repair could be made by a repairman.
 
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Each of them took a room and worked toward the middle of the house in their search, all lights having been turned on to give maximum illumination. The job was no easy one. Even the slightest crack anywhere would be sufficient to cause the loss of pressure; it was just like a tire tube with a tiny puncture. Ted was the first to finish his assigned area. He had found nothing. Presently Randy was through, then Mrs. Kenton, then Jill. No one had found a leak anywhere, and the entire house had been covered.
 
“We must have missed it somewhere!” Ted said. “We’ve wasted a whole hour!”
 
“The spare cartridges your father told us to have filled!” Randy suddenly exclaimed. “We didn’t do it!”
 
“We forgot to in all the excitement after he left!” Ted groaned.
 
“What’ll we do?” Mrs. Kenton asked, horrified. “In another hour or so, we’ll have used up the air in our suits!”
 
“Can’t we refill our suit cartridges from the air drum downstairs?” Jill asked.
 
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Ted shook his head. “It’s not built that way.”
 
“Then we must phone for help right away,” Mrs. Kenton said and rushed off to the radiophone.
 
In a few moments she was back. “They’ll send someone from town with spare cartridges right away,” she said, “but the man said we couldn’t get a repairman until morning to fix the leak. We’ll have to stay in our space suits if we don’t find the leak.”
 
“Then let’s look for it again,” Ted suggested.
 
Once more they spread out all over the house, but this time they changed areas, so that if a mistake had been made before there was less chance of repeating it this time. They renewed their search, and it was not until all were through, again without having found the leak, that they realized that another hour had passed and the man with the spare cartridges had not shown up.
 
“The gauge in my helmet shows I’ve got only ten minutes of air left!” Jill said.
 
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The others checked their gauges. All showed about ten minutes’ supply remaining. And there was no guarantee that the spare cartridges would arrive in that time.
 
Just as Mrs. Kenton was going to the radiophone to call the air-supply center again, the phone buzzed and she answered it. After listening a moment, she turned to the children with a white face. “............