"I'm not even sure it is a plague," growled Steel, sinking into his chair. As usual, it groaned under his weight, and he cursed it absently. "It doesn't act like a plague, doesn't feel like a plague-" He took another bite from his candy bar and wiped his sticky fingers on his short front. The sugar gave him energy. "What kind of a plague doesn't have any symptoms? One minute the victims are fine and healthy, and the next minute they and everyone around them is either dead or mad. No plague works that fast."

"Could be a long incubation period."

"No. Our tests would have found something by now."

"Well what is it, if it isn't a plague?"

"I don't know! Some new Empire weapon, a rogue esper . . ."

"An esper? Be serious, Steel. What kind of esper could take out five thousand people in less than a week?"

"You once stood off five hundred Guards with a single song."

"Yes," said Topaz steadily. "And it nearly killed me. I'm the most powerful Siren the Empire ever discovered, and even I have my limits. No, Steel; it can't be a rogue esper."

"You can't be sure of that."

"We can't be sure of anything anymore, Director."

Steel and Topaz glared at each other helplessly, and then looked away as the command monitor snapped on.

"Director!"

"Yes, duty esper. What is it?"

"Sensors report a gathering of Empire ships off Mistworld, Director."

Steel gaped at the screen, unable to take the news in.They've come. They've finally come . He swallowed dryly, and shook his head slightly to clear it.

"How many ships?"

"Seventy-three and counting, Director. They're dropping out of hypers.p.a.ce as we watch."

"It's the Fleet," said Topaz softly. "After all these years, the Empire finally thinks it's ready to destroy Mistworld."

Steel ignored her, and broke contact with the duty esper to key his monitor into the main system. The screen showed him a crowded radar image, with new contacts appearing every second. Overlapping voices from the command centre filled the cubicle.

Disrupter cannon don't answer to the computers. Get a team down there to check the systems.

Smuggler ships are powering up for takeoff. Ground crews please clear Pad Seven.

Where are the espers? We need the psionic shield.

Force shields are down. They don't answer to the computers.

Disrupter cannon are not on line. Repeat; disrupters are not on line.

The computers are dead! They don't hear us!

Where are the espers?

Steel cleared the screen, and the voices fell silent. He could feel his pulse hammering in his neck, and his palms were wet with sweat. Everything was happening so d.a.m.ned fast . . . He looked at Topaz, and her unruffled self-possession helped to calm him down a little.

"We've still got the smugglers' ships," said Topaz.

Steel shook his head. "They don't stand a chance against the Imperial Fleet, and they know it. They're going to die up there, just to buy us a little time." He sat back in his chair and stared dazedly round his cubicle. Beyond the gla.s.s walls, technicians were running back and forth, shouting and cursing silently.

"The force shields are out. The disrupters are out. I can't believe our defences all fell apart so quickly.

What the h.e.l.l's happened to our computers?"

"The crystal!" said Topaz suddenly.

"What?"

"The memory crystal I delivered; it was part of the main defence systems, wasn't it?"

Steel swore softly. "Yes, it was. Your burglar must have had time to switch crystals before you discovered him. And what with all the excitement of theBalefire arriving, and the Hob hounds, and the plague . . . the crystal must have been installed without checking."

"And I never thought to check for myself."

"No reason why you should have; that was our responsibility."

A distant roar shook the control tower as the smugglers' ships threw themselves into the night skies, a dozen silver needles against the Imperial Fleet.

"Call them back," said Topaz.

"I can't. We need time to bring the espers together. Without our shields and disrupters, the smugglers'

ships are the only other defence we've got left. Their names will be remembered as heroes."

"We're going to lose," said Topaz quietly. "I should have known. I should have known there was nowhere safe from the Empire."

Steel glanced quickly at her dark, brooding face, and then turned back to his command monitor and raised the duty esper.

"Gather the espers. We need the psionic shield."

"It's already up and holding, Director, but I don't know how long we can maintain it." John Silver's face was calm and controlled, but his eyes were grim. "Hundreds of espers have died from the plague."

"That's it!" Steel turned to his computer console, ignoring the startled esper, and tapped in a query. He nodded savagely as a stream of information flowed across the screen. "I should have seen it before;only espers have died from the plague. We were so busy looking for a physical common denominator we didn't think to check for any other links. Investigator, we've been set up. With our computers sabotaged, the psionic shield is all that stands between us and the Fleet, and the plague was introduced specifically to take care of that. And I was so proud of my cannon . . . I should have listened to Suzanne du Wolfe.

Duty esper, maintain the shield. That has top priority until I tell you otherwise."

"Yes, Director, but . . ."

"Just do it!" Steel broke off contact and stared thoughtfully at the blank monitor screen. "It's a carrier, has to be. One of the refugees from theBalefire . I thought Starlight was lucky to escape from Tannim!

Somewhere along the line the Empire must have smuggled aboard a carrier with an esper-specific plague."

"No," said Topaz abruptly. "That's not it." Steel looked at the Investigator in surprise as she paced back and forth before him, frowning. "You were right the first time, Director; it's not a plague, it's a rogue esper. A Siren, like me. When I sing, my voice and esp combine to work directly on the mind, boosting and scrambling the sensory input. Take that too far, push too hard . . ."

"Brainburn," said Steel.

"Yes," said Topaz. "That's what happened to the five hundred Guards on Virimonde."

"And if you were to sing at an esper . . ."

"The weaker mind would self-destruct. The victim's talent would rage out of control, attacking both the victim and his surroundings. It's no wonder so many plague sites have been gutted by fire and violence; the victims must have included Pyros and Poltergeists. How could we have been so blind? The espers were the real target all along. The mindwiped survivors were nothing more than innocent bystanders; a blind to keep us from noticing that one by one those we depended on most for our defence were being murdered!"

Steel and Topaz looked at each other.

"You were the most powerful Siren the Empire ever had," said Steel finally.

"Yes," said Topaz. "I was. I destroyed five hundred minds, and they made me a legend. This new Siren has taken more than five thousand victims, in just a few days. I wonder if they'll make her a legend too.

Probably not; she'd more valuable as a weapon." Topaz shook her head slowly. "No wonder the port espers picked up strange readings from theBalefire . Director, we've got to find this rogue and stop her, while we still can."

Steel frowned thoughtfully. "It's not going to be easy, trying to find one woman in a city the size of Mistport. I take it we can be sure the rogue is a woman? If the empire's finally produced a male Siren . .

Topaz shook her head firmly. "No, it's a s.e.x-linked characteristic, like hexing or dowsing."

"Let's hope you're right, Investigator." Steel called the duty esper back to his monitor.

"Yes, Director?"

"How many espers can you spare me for a city-wide search? Emergency priority."

"a.s.suming everyone reports in, maybe a dozen; but that'll be most of our reserve."

"I'll take them. We're looking for a rogue esper, a very powerful Siren. You shouldn't have much trouble recognising her; she was responsible for the strange readings your people picked up from theBalefire .

Report back to me as soon as you've found her, but no one's to approach her until I give the word. This rogue is dangerous. Got it?"

"Yes, Director."

"Is the shield secure?"

"For the moment. The Empire ships are in stable orbit, but keeping their distance. They know what will happen if they try anything."

"Stay with it, lad," said Steel gruffly, and John Silver grinned.

"With our shield or on it, Director."

The monitor screen cleared. Steel looked in surprise at his last piece of candy, melting forgotten in his hand, and popped it into his mouth. He chewed thoughtfully, his hands clasped across his belly. "The port espers scanned every man, woman, and child leaving theBalefire . There's no way the rogue could have got past them."

Topaz shrugged. "Empire agents must have got to her first, and spirited her off the landing field. This whole thing has been very carefully planned, right from the beginning."

"It's starting to look that way. But how far back does this thing go, Investigator? Did the Empire really scorch Tannim lifeless just to make sure we'd accept theBalefire' s refugees? A whole world?"

Topaz looked at him steadily. "They've done worse, Director. Much worse."

They sat in silence a while. Steel knew there were things he ought to be doing, but somehow he just couldn't seem to raise the energy. "Do you think they'll find the rogue, Investigator?"

"A dozen espers, to cover an entire city? They might get lucky, but I doubt it. We don't even know her name."

"Call her Mary."

"What?"

"Typhoid Mary. It's an old name for a fugitive carrier of disease." Steel smiled at Topaz's open astonishment. "A Port Director has to study many fields, Investigator."

He steepled his fingers and tapped them together thoughtfully. "As from now, I'm promoting you to Watch Commander. With the Bloodhawk missing, I need someone on the spot I can trust. You're probably the only one in the Watch who really understands what we're up against. Get all the Watch out on the streets and search the city, sector by sector. If you come across any espers apart from the rogue, I want them escorted here under full protection. We can't afford to lose any more espers. At least here we should be able to offer them some security."

Topaz nodded. "Sounds logical. Just one thing; what are my men supposed to do if they find the rogue?"

"They can't afford to take chances," said Steel steadily. "Keep her under surveillance, but don't approach her. I'll send men armed with disrupters."

"You're not going to give her the chance to surrender."

"No. I can't take the risk."

"With this many Watch out on the streets, we're going to need a cover story."

"Right. If the truth gets out there'll be a panic. Put a bounty on the rogue's head and tell everyone she's a plague carrier. It's true enough."

Topaz smiled slightly. "That should keep people off the streets. I'll lead a patrol into Thieves Quarter. I know the area."

"No! You're an esper, Topaz; I can't risk losing you to the rogue."

"I'm a Siren, Director. I may be the only real chance you've got of stopping her."

Steel hesitated, and then nodded curtly. He turned away and studied his computer console, and after a moment Topaz left the cubicle. Steel scowled at the blank screen before him. d.a.m.n fool woman was going to get herself killed at this rate. He wondered why that bothered him so much. He sighed wearily, and indulged in a long, slow stretch. He was so tired even his bones ached. He'd done everything he could, but he had a strong feeling it wasn't going to be enough. The Empire had been planning this for a long time. They wouldn't have left anything to chance. He blinked in surprise as his monitor screen suddenly lit up again.

"Yes, duty esper. What is it?"

"Hob hounds, Director! They're pouring into the city through a breach in the Guilds Quarter boundary.

First reports are confused, but it seems clear there are hundreds of the beasts. The Watch on the spot are falling back, street by street. Without reinforcements, it's only a matter of time before they're overrun."

"Of course," said Steel. "The Empire can't risk us finding Mary too soon, so they provide a distraction.

Logical."

"Director?"

"Take as many Watchmen as you need, but I want those hounds contained. It's vital they be stopped where they are."