"Mr Rubilio! Shut off all feeds to the ship's information channels! Announce a technical problem!"

"Yes, Captain."

"Mr Berry! If you continue, you will be guilty not only of disobeying a lawful order, but of a piratical act! Do you understand?"

She listened, was silent for a moment, then replied, "No." Her voice was puzzled, its pitch even higher.

"Mr Berry, we all appreciate that you've had a difficult and stressful experience during the wall passage. You are exhausted and you appear to be delirious. We've reached the edge of the wall and the ship is safe, thanks to you. We will now continue our journey back into the local bubble in the normal fashion. But first, please stop, take off your mask, rest, rejoin us and recover."

"What's this 'wall'?" she asked, her voice irritated.

"Why don't we just pull her off the stage?" an irritated voice whispered.

"Don't try it!" Her voice was full of menace.

"Just disconnect her!"

 "She seems to have grabbed the system off us! Wherever she is in the ship, Gillian's still at the ship's helm as long as she's in her Walk Suit. We can't disconnect her!"

Someone whispered, "What's wrong with her speech? She sounds almost like a three year or four-year old child!"

A more gentle voice spoke. "Gillian, this is Doctor Morris. You were navigating a passage thought the wall to get us back to the local bubble. Do you remember?"

"Of course I remember the passage. But it isn't a wall!"

 "Gillian, try to recall where you are and what you're supposed to be doing. You were piloting the ship through a wall of macro-quantum objects."

She was still irritated. "It's not a wall, you idiots!"

"Well, what is it?"

"It's a vent blade - a fan! There are hundreds of them. They keep the bubble clear." She made an effort to talk slowly and clearly. She tried to be patient with them, but she was edgy and irascible. She was in a hurry.

"Dr Morris! What's wrong with her?"

"According to these readings, she's asleep. She's sleep walking!"

"I don't believe it! She's clearly had a breakdown of some sort. She's psychotic!"

"No, really, Gillian is asleep!"

She was irritated. "Nonsense! I'm wide-awake. And you've just taken your ship through a galactic ventilation mechanism. It could have done significant damage. It was foolish and irresponsible!"

"What is she talking about? The girl's delusional."

A new voice spoke. "How many more of these things exist, Gillian?"

She forced herself to be patient. "As I said, there are hundreds of them!"

"Where are they?"

"Here are four examples." She gave several sets of galactic coordinates, speaking slowly, as if in her child's voice she was talking to simpletons.

"Mr Rogers, examine those locations, would you?"

"Yes, Captain."

The little girl's voice announced,  "Now that we're safely back in the bubble, in a few minutes, I'm going to take us on three big jumps. I'll have us home in half an hour!"

"Captain! The woman is psychotic. She shouldn't be at the helm of the ship. You should disconnect her and drag her from that stage!"

"We can't do that, Mr McWhirter. She's taken control of the ship's systems. She can Walk from any location. The stage is just a convenience."

"Are our starships so vulnerable that they're at the mercy of a Walker's sanity? Mr Dryen? Mr Yegg?"

"We always have weaknesses, McWhirter. And on this ship, we've been forced to revert to an older version of the system. The vulnerability must result from that incident the other week. Do you remember when she crashed part of the nav module, Mr Dryen?"

"Yes, she wriggled her toes, when they weren't there in the simulation. She must have detected other logical weaknesses."

"Mr Dryen, what are the consequences of taking the kind of Walk she just described?"

"The usual ones, Captain. If you take a big step, say one light year long, something hazardous may have appeared in the target location during the last year. We won't know about it. The bigger the step, the bigger the risk. If she's walking back to Sol in a few steps, it means tens of light-years for each step. The risks increase almost geometrically. There are many unknown objects out there. The chance is low, but we could hit an orphaned planet, a small ultra dense cloud, a lost century ship - its endless!"

She was listening, and still irritated. "You fools, I can avoid that danger!"

"Why does she sound so much like a child?"

 "Captain!"

"Yes, Mr McWhirter?"

"Based on what we've just heard, I will support you if you order the Marines to shoot her."

A young woman screamed in panic: "Gillian! Take off your mask! Please! Come down off that stage!"

Another voice yelled: "Captain! You can't have her shot!"

 "I can have her shot, Mr Yegg. My authority is supreme on this ship! She is a fraud, and a danger to the ship. Are you aware she had her parents hidden on the ship under a false name? The youth who attacked her informed us. He'd been stalking her. We've taken the parents into custody, in the second wheel."

Abel was dismissive. "We knew of the Berry couple. They seemed harmless to us."

"If you knew about them, it was your duty to inform the Captain!"

"It's alright, Mr McWhirter, I knew before Mr Yegg did, and so did you. Let's not argue that point now. But Mr Yegg, we can no longer assume the Berrys' are harmless. It may be that they carry the same type of - shall I say 'infection'? - as their daughter."

She was annoyed. "I don't care what you do with the old people! Be Quiet! Let me concentrate!"

 "Captain! I absolutely forbid you to shoot that young girl!"

"Mr Barry, you have no authority here."

"I claim the authority of common decency, Captain!"

"You may claim nothing here, Mr Barry."

She said, "If you're planning aggressive action, then be warned. I am not defenceless."

"Captain, my team just examined the coordinates given us by Gillian. Our instruments see indications of more gigantic macro-quantum walls at those locations. They reach into the clouds, and each is bounded horizontally by black holes."

She said, "Now will you believe me!"

 "Amazing news, Mr Rogers! But we must deal with the current problem. I'm inclined to agree with Mr McWhirter's recommendation."

 "Captain, it's clear that we have an alien intelligence on this ship, and we must either control it, or eliminate it!"

 "Captain, you cannot shoot that beautiful young girl!"

"I can shoot, Mr Barry, and I will shoot her if I must - reluctantly. My authority is absolute, but I accept the advice of Mr McWhirter in this matter."

"Brace yourselves!" she yelled in her piping child's voice. "This won't be like one of your ridiculous little Walk steps!"

"Gillian, stop! Don't you remember me - Celia?"

"No."

"Look at her! She's doing a funny little dance!"

"Look at the weird way her feet are twisting and kicking!"

"If I arched my back that far I'd break my spine!"

Everyone in the Navigation Centre gasped or screamed. The ship seemed to be turning inside out.

"Marines, open fire!"

"Stop! Stop!"

"Mr Barry, get down off that stage, you fool!"

Simultaneously, there were three or four loud popping noises.

Silence fell for a moment. A young girl cried out, "Gillian!"

"Is she dead?"

"I hope not, Mr Yegg. But Mr Barry took a couple straight in the chest when he jumped in font of her. Mr Dryen, where is the ship now?"

Mr Dryen's voice trembled. "It's certainly nowhere near the Earth system, Captain. I don't know where she thought 'home' was. But we've travelled more than a hundred light years back into the local bubble!"

"Nurses! Get that mask and skin suit off Mr Berry! Immediately!"

"Yes, Captain!"

"Is she still alive?"

"No, no! Not right there on the stage! Have some decency! Take her behind that little changing cubicle!"

 "What made Mr Barry behave like that?"

 "Dr Morris, will you make appropriate arrangements for Gillian - " The voice trembled for a moment. "- for Mr Berry - please? Either the mortuary or the hospital. And our impetuous Mr Barry, too."

"Yes, Captain."

 "Mr Rubilio, organise a check for damage to the ship."

"Yes, Captain."

"And Dr Morris, I don't mean the passenger mortuary or hospital. Take Mr Berry to the second wheel. I want her isolated, along with her parents. And hold them separately!"

"Yes, Captain!"

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