The signal was not a voice.
Uhura had established that much before Kirk got across the terrace.
He came the length of it with the communicator at his ear and static washing over half her words, while behind him Scott packed up in ninety seconds the work area he had spent an hour arranging, and McCoy stood between Ostrow and the western path like a man heading off a horse.
"Say again, Lieutenant."
"No modulation consistent with speech, sir. No carrier structure I recognize. It repeats, but not at regular intervals."
Morbius had come out into the doorway. Whatever Kirk had seen on his face when the transmission was first reported had been put away, and what was there now was the controlled courteous face he had worn since the Enterprise arrived. Kirk had begun to distrust that face a good deal more than he would have distrusted anger.
"Doctor. What is transmitting under your house?"
"Nothing that I have activated."
"That isn't what I asked you."
"Then I cannot answer you."
Kirk raised the communicator again. "Can you localize it?"
Interference nearly ate the reply. "Within two hundred meters horizontally. Depth uncertain. Mr. Spock says the source is moving."
That reached Morbius. Not far. A tightening at the corner of the mouth.
"Moving how?" said Kirk.
Spock's voice came in over Uhura's. "Not geographically, Captain. The emission point remains beneath the plateau. The signal is appearing through different portions of the subsurface power network. It may be using the network rather than originating from any single transmitter."
Scott snapped the first case shut. "Like a man talkin' through whichever wire happens to be nearest."
"An imprecise analogy, Mr. Scott. It is adequate."
Scott looked at Kirk. "He's been saving that one up."
"Spock, any effect on the ship?"
"Surface telemetry is degraded. Communications are functional at present. Sensors are returning false depth values from beneath the plateau."
"Weapons?"
"Unaffected."
"Transporters?"
A pause that Kirk did not care for at all. "Intermittent."
He looked at his chief engineer. "Get back aboard while you still can. I want you in engineering if this gets any worse. Take your people."
Scott did not like leaving the android, or the converter, or an unsolved problem, and he liked being away from his engines during something that might turn into an attack a great deal less.
"Aye, sir." He closed the second case, and then looked at Robby, who was still holding a duplicated hyperspanner and two bottles of whisky that had acquired, in the last half hour, a surprising emotional significance. "You'll mind those."
"I will."
"Particularly the whisky."
"Yes, Mr. Scott."
Scott hesitated. "Captain, he is definitely mockin' me."
"Go."
He went. Kirk stayed where he was until the transporter took Scott and his two engineers off the plateau. The shimmer broke once at its edges, reformed, and cleared.
"Spock. Beam down as soon as Mr. Scott reports clear."
Morbius turned. "Why?"
"Because if something under your house has decided to introduce itself to my ship, I want my science officer standing where the introduction starts."
"You have a xenoarchaeologist."
Ostrow had moved along the terrace wall and was listening to the communicator as though the static itself might turn out to have a grammar.
"Doctor Ostrow is staying above ground," said McCoy.
Ostrow turned his head. "I was not aware that you had acquired command authority, Doctor."
"I've got medical authority, and today that's near enough."
"My pulse is normal."
"You don't know that."
"I can count."
"So can I," said McCoy, "and I own the scanner."
The argument might have gone several more rounds if the ground had not moved.
It was not an earthquake. Kirk had been through earthquakes, explosions, impacts, and the particular sick lurch of a starship deck when the inertial compensators go. This was none of those. For rather less than a second the terrace seemed to pull sideways beneath his boots without going anywhere at all. The stone stayed where it was. His inner ear insisted, with some heat, that it had not.
Alta caught the back of the chair beside her. The tiger came up off the ground in one movement. Robby turned toward the ridge.
Every light in the house went out, and then came back.
Morbius moved first, and not toward his daughter. He went to a panel beside the door.
"That system is independent," he said.
Kirk watched his hands go over the controls. "Apparently not."
"It has no physical connection to the lower installation."
"Apparently it does."
Morbius looked up at him sharply, and whatever he had been about to say was lost, because Spock arrived.
The beam came down hard. It took four seconds longer than it should have, and held him half formed for part of one of them, and Kirk, who had watched a great many transporter cycles, felt the back of his neck go cold. Then it let go, and Spock was standing on the terrace with his tricorder already open, as though nothing whatever had happened, his way of reporting that something had.
"Captain."
"You felt that shear?"
"The Enterprise registered a transient gravitational shear of negligible magnitude."
McCoy stared at him. "Negligible."
"No structural damage occurred."
"I know what the word means, Spock."
Spock crossed to the edge of the terrace and held the tricorder down toward the ground, and Ostrow was at his shoulder before McCoy could open his mouth.
"The signal changed," Ostrow said.
"You can hear it?"
"No. The interval shortened after the shear."
Spock checked. "Correct."
Kirk looked from one Vulcan to the other. "Meaning what?"
"Possibly nothing."
"And possibly?"
"A response," said Ostrow.
Morbius laughed once, and there was nothing in it. "To what?"
Nobody answered him. That was becoming a habit on that terrace.
The communicator sounded. "Bridge to Captain Kirk."
Sulu.
"Kirk here."
"Sir, we took a navigation error off the planetary horizon sensor. It corrected itself inside a second, but the computer briefly put our altitude at negative eleven kilometers."
"That's inconvenient," said McCoy.
"Actual orbit, Mr. Sulu?"
"Stable, sir."
"Keep it that way. Anything else changes, I want to hear about it before the computer does."
Spock had gone down on one knee and laid his hand flat against the terrace stone.
Morbius watched him. "You will learn very little through your fingers."
"I am not using my fingers."
The tricorder gave out a short sequence of tones, and Spock stood.
"The signal is not directed at the Enterprise."
"Uhura says it's reaching the ship."
"It is. That is not the same thing."
Ostrow had it first. "It is broadcasting."
"Yes."
"To whom?" said Alta.
Spock looked across the terrace at Robby, who had not moved from the edge of it since the ground shifted. "That is what I intend to determine."
Robby turned around. "It is not for me."
Morbius's head came up. "You recognize it."
"No."
"You have just said that it is not for you."
"I know the difference," said Robby.
Kirk came a step closer. "Between what?"
"Between a command and an inquiry."
The distinction went out across the terrace and settled on all of them.
"This is an inquiry," Spock said.
"Yes."
"What is it asking?"
"I do not know."
"That is impossible," said Morbius, coming down the steps.
"No."
"If you can identify its function you can identify its content."
"No."
"Robby."
The android stood still, and Kirk watched the old pattern run again: the man asked a question, got no useful answer, and heard disobedience.
It was Spock who broke it. "Robby. Does the inquiry require an answer?"
"I do not know."
"Could answering it cause harm?"
The pause was longer than any he had given them. "Yes."
"To whom?" said Morbius.
"I do not know."
Kirk made the decision standing up. "Then nobody answers it. Not you, not my ship, not anything on this plateau."
"Captain," said Morbius, "you do not even know what you are refusing."
"That's correct."
"And that does not trouble you?"
"Not nearly as much as how little it troubles you."
For a moment the younger man showed through the older one, the man who had gone down into a chamber alone in the dark because not knowing what a thing did had become intolerable.
Then the house lights dimmed a second time, and the tiger began to growl.
Not at anyone on the terrace. At the air beyond it.
Every head turned. The animal had gone low, shoulders up, ears flat, the whole of its attention on a point some twenty meters out past the garden where there was nothing to see.
Alta put a hand on its neck. "Easy."
It did not move.
"Captain," said Spock, raising the tricorder.
Kirk had his phaser out. "I have it."
McCoy came off the wall. Ostrow stepped behind the terrace wall without being told, which was the most sensible thing Kirk had seen him do in two days. Morbius did neither.
"There is nothing there," he said.
The growl went down an octave.
Spock swept the empty ground twice. "No life form. No coherent energy pattern."
"Robby?"
The android looked at the same piece of nothing. "I see nothing."
Kirk had read that sentence at two in the morning in a twenty-year-old incident report, filed by a captain who had been dead for two decades, about a door that had opened itself.
Not: I failed to observe anything.
I see nothing.
Then the garden path bent.
It happened for a fraction of a second and not enough of one that Kirk could have sworn to it under oath afterward. The line of pale stones along the path seemed to deform around an outline that had no color of its own, the way a spoon deforms in a glass of water.
And then the equipment shed at the end of the garden came apart.
There was no explosion. That was the part Kirk reported afterward that nobody at Starfleet Command ever quite accepted. The shed did not blow outward and it did not fall in. Its panels separated along their seams, all of them at once, and went down onto the stone in an order so neat that it looked deliberate, and the frame stood a moment longer and then came apart too, section by section, and lay down.
Ensign Rivera had been standing four meters from it.
Kirk saw him go. There was no impact he could point to and nothing that struck the man, only Rivera leaving the ground and traveling six meters through the air and coming down on his shoulder on the stone at the edge of the terrace, hard, his phaser going off into the sky as he fell.
McCoy was moving before he landed.
"Spock!"
"No reading, Captain. Nothing."
The tiger lunged forward one full step and Alta went with it, both hands in the fur, her boots sliding on the stone, and Robby was there before Kirk could shout, one hand flat against the animal's chest, immovable as a wall.
Then the communicator at Kirk's belt shrieked with static, and Uhura's voice came through it.
"Captain, the signal has stopped."
Kirk did not lower the phaser. "Spock."
"Confirmed. The local distortion has also ceased."
The tiger stayed exactly where it was, staring at the empty garden, and went on staring at it long after the rest of them had turned away.
McCoy had Rivera's tunic open. "Dislocated shoulder, three ribs, possible concussion. He'll keep, but he's going up now."
"Take him."
Kirk turned around, and Edward Morbius was standing in the middle of his own terrace, entirely white in the face, looking out at the garden where the light had bent.
"What did you see, Doctor?"
"Nothing," said Morbius.
It was the wrong answer, and Kirk knew it was wrong for the same reason he had known it in the house the day before.
The man had answered far too quickly.
* * *
They spent the next three hours establishing almost nothing, and Kirk made every one of them count anyway.
Spock found a transient distortion in the local field, too weak and too incomplete to classify, occupying roughly two cubic meters and possessing, in his words, no measurable mass, charge, temperature or intention, the last of which he defended when McCoy objected to it, on the grounds that it was the only honest word available.
Ostrow, working on the tricorder record of the last eleven seconds of the underground signal, found a repeating sequence that might have been a Krell interrogative.
"Might have been," Spock said.
"Three of its relationships are inadmissible."
"Inadmissible according to what?"
"According to every rule I have derived in six years," said Ostrow, and then sat down on the terrace wall with the instrument in his hands, and did not say anything else for some while, and Kirk left him alone, because he had seen men take that particular news before.
The shed was recorded where it lay. Nothing was missing from it. Nothing was broken. Two hundred and six components were on the ground in the order in which they had come out, and one of Scott's engineers, going over the record from orbit, observed that whoever had done it had begun with the fasteners.
Morbius offered no help whatever, and that, more than anything else on that terrace, convinced Kirk the man knew something.
At sunset the Enterprise got clean telemetry back. Transporter locks steadied. The false navigation values stopped. Rivera woke up in sickbay and asked, through the concussion, what had hit him, and McCoy told him the truth: nothing had.
The crisis, if it had been one, appeared to be over.
Kirk did not believe it for a moment.
McCoy found him at the western edge of the terrace watching the light go off the ridge.
"You planning to stand out here until the next invisible thing comes by?"
"Possibly."
"Fine. I'll have dinner sent out."
Kirk looked back toward the house. Alta was inside, sitting on the arm of a chair with a communicator against her ear, talking to Uhura. The two of them had spoken three times since the Enterprise made orbit, briefly, twice at McCoy's suggestion and once, Kirk noticed, at neither's. Alta asked questions about the ship. Uhura answered all of them.
Morbius had disliked that as much as he had disliked anything else that had happened today.
"Bones."
"Mm."
"Tomorrow I want Alta aboard for a few hours."
McCoy's expression changed. "Medical reason?"
"Human reason."
"Her father will fight you on it."
"He can try."
"Are you asking her, or telling her?"
Kirk weighed that, and McCoy smiled very faintly.
"Good answer."
Behind them, through the open window, Alta laughed at something Uhura had said.
Morbius came into the room at the sound of it.
Kirk watched him stop, for no longer than a step, in the middle of his own floor.
Then he kept walking.
