There was a low growl from the control room.
"Oh, my God!" Arnold gasped. He concentrated furiously for a few seconds. "I know. I left the airlocks open when I landed. We're still breathing Ghost V air!"
And there, framed in the open doorway, was an immense grey creature with red spots on its hide. It had an amazing number of arms, legs, tentacles, claws and teeth, plus two tiny wings on its back. It walked slowly towards them, mumbling and moaning.
They both recognized it as the Grumbler.
Gregor dashed forward and slammed the door in its face. "We should be safe in here," he panted. "That door is airtight. But how will we pilot the ship?"
"We won't," Arnold said. "We'll have to trust the robot pilot — unless we can figure out some way of getting that thing out of there."
They noticed that a faint smoke was beginning to seep through the sealed edges of the door.
"What's that?" Arnold asked, with a sharp edge of panic in his voice.
Gregor frowned. "You remember, don't you? The Grumbler can get into any room. There's no way of keeping him out."
"I don't remember anything about him," Arnold said. "Does he eat people?"
"No. As I recall, he just mangles them thoroughly."
The smoke was beginning to solidify into the immense grey shape of the Grumbler. They retreated into the next compartment and sealed the door. Within seconds, the thin smoke was leaking through.
"This is ridiculous," Arnold said, biting his lip. "To be haunted by an imaginary monster — wait! You've still got your water pistol, haven't you?"
"Yes, but —"
"Give it to me!"
Arnold hurried over to a water tank and filled the pistol. The Grumbler had taken form again and was lumbering towards them, groaning unhappily. Arnold raked it with a stream of water.
The Grumbler kept on advancing.
"Now it's all coming back to me," Gregor said. "A water pistol never could stop the Grumbler."
They backed into the next room and slammed the door. Behind them was only the bunkroom with nothing behind that but the deadly vacuum of space.
Gregor asked, "Isn't there something you can do about the atmosphere?"
Arnold shook his head. "It's dissipating now. But it takes about twenty hours for the effects of Longstead to wear off."
"Haven't you any antidote?"
"No."
Once again the Grumbler was materializing, and neither silently nor pleasantly.
"How can we kill it?" Arnold asked. "There must be a way. Magic words? How about a wooden sword?"
Gregor shook his head. "I remember the Grumbler now," he said unhappily.
"What kills it?"
"It can't be destroyed by water pistols, cap guns, firecrackers, slingshots, stink bombs, or any other childhood weapon. The Grumbler is absolutely unkillable."
"That Flynn and his damned imagination! Why did we have to talk about him? How do you get rid of it then?"
"I told you. You don't. It just has to go away of its own accord."
The Grumbler was full size now. Gregor and Arnold hurried into the tiny bunkroom and slammed their last door.
"Think, Gregor," Arnold pleaded. "No kid invents a monster without a defence of some sort. Think!"
"The Grumbler cannot be killed," Gregor said.
The red-spotted monster was taking shape again. Gregor thought back over all the midnight horrors he had ever known. He must have done something as a child to neutralize the power of the unknown.
And then — almost too late — he remembered.
Under auto-pilot controls, the ship flashed Earthwards with the Grumbler as complete master. He marched up and down the empty corridors and floated through steel partitions into cabins and cargo compartments, moaning, groaning and cursing because he could not get at any victim.
The ship reached the solar system and took up an automatic orbit around the moon.
Gregor peered out cautiously, ready to duck back if necessary. There was no sinister shuffling, no moaning or groaning, no hungry mist seeping under the door or through the walls.
"All clear," he called out to Arnold. "The Grumbler's gone."
Safe within the ultimate defence against night horrors — wrapped in the blankets that had covered their heads — they climbed out of their bunks.
"I told you the water pistol wouldn't do any good," Gregor said.
Arnold gave him a sick grin and put the pistol in his pocket. "I'm hanging on to it. If I ever get married and have a kid, it's going to be his first present."
"Not for any of mine," said Gregor. He patted the bunk affectionately. "You can't beat blankets over the head for protection."