"Knowing that you are well and prosperous is thanks enough. Now I must go."

"We must talk first," Kovacs said. He told his driver to wait, and led the way back into the lab. "There is no one here," he said.

They passed through lab rooms filled with electrical contraptions that would have been at home in Frankenstein's lab and settled in a luxurious office.

"You've done well," Schroeder said. "I'm glad to see that."

"I've been very fortunate. And you?"

"I am happy, although my home isn't as rich looking as yours."

"You've been to my house? Of course, I should have known. You touch all the bases, as they say in our adopted country."

"You have a family?"

A cloud passed over Kovacs's brow, but then he smiled. "Yes, I remarried. And you?"

"There have been many women, but I continue to be a loner."

"Most unfortunate. I'd like to introduce you to my wife and daughter."

Schroeder shook his head. This was as far as it goes, he said. Kovacs said he understood. Schroeder's presence would raise too many questions. Both of them still had enemies in the world. They talked for another hour, until Schroeder finally asked the question that had been on his mind.

"I assume you have buried the frequencies?"

Kovacs tapped his forehead. "Up here, now and forever."

"You are aware that there was an attempt to capitalize on your work. The Russians found material at the lab and tried to make it work for them."

Kovacs smiled. "I am like the aunt who writes down her cookie recipe for the family but leaves out an important ingredient. Their experiments would have taken them only so far."

"They tried. Our adopted country conducted similar research, once the government found out what was going on. Then the experiments stopped."

"There is no need to worry. I haven't forgotten what my work did to my first family."

Satisfied with the answer, Schroeder said he had to go. They shook hands and embraced. Schroeder gave Kovacs an address to get in touch with him, if needed. They vowed to talk again, but years passed without contact. Then one day, Schroeder checked his blind box and found a message from the Hungarian.

"I need your help again," the message said.

When he called, the scientist said, "Something terrible has happened."

This time, Schroeder went directly to the Grosse Pointe mansion. Kovacs greeted him at the door. He looked terrible. He had aged well, the only visible change a graying of his hair, but there were dark circles under his eyes, and his voice was hoarse, as if he had been crying. They sat in the study, and Kovacs explained that his wife had died a few years before. Their son had married a wonderful woman, he said, but they were both killed in a car crash a few weeks before.

When Schroeder offered his condolences, Kovacs thanked him, and said there was one way he could help. He spoke into an intercom, and a few minutes later a nursemaid came in. She was holding a beautiful, blond baby girl.

"My granddaughter, Karla," Kovacs said, proudly taking the baby. "She is named after an old friend who, I hope, will soon be her godfather."

He handed the baby to Schroeder, who held her awkwardly in his arms. Schroeder was touched by the invitation and accepted the responsibility. As the girl grew up, he made several trips to Grosse Pointe, where he was referred to as Uncle Karl, and had become entranced by her grace and intelligence. On one occasion, she and her grandfather had spent several days in Montana. They were sitting on the porch of his log cabin, watching the girl chasing butterflies, when Kovacs revealed that he had a fatal illness.

"I am going to die soon. My granddaughter is well provided for.

But I want you to pledge that you will watch over her as you once watched over me and protect her from all harm."

"It will be my pleasure," Schroeder said, never dreaming that one day he would have to honor his pledge.

The last time he had seen Karla was at her grandfather's funeral. She had started college and was busy with studies and friends. She had developed into a lovely and intelligent young woman. He checked in with her from time to time to make sure she was well, and followed her career with pride. It had been years since they had seen each other. He wondered if she would recognize him.

He clenched his teeth in renewed determination.

Whatever it took, he knew he must get to her before they did.

The intruder slithered through the dark water in an explosion of bubbles that scattered schooling fish like windblown leaves. As the five-foot-long torpedo flew through the sea, the transducer pulsing under its metal skin bounced high-speed bursts of energy off the bottom. An electronic ear collected the returning echoes, and the data from the sonar tow fish flew at the speed of light along an armored fiber-optic cable hundreds of feet long. The thick cable snaked onto the deck of the turquoise-hulled ship plowing a foamy wake through the ocean about two hundred miles east of the mid-Atlantic coast of the U.S.

The cable terminated in the survey control center on the ship's main deck. Austin sat in front of a glowing screen, analyzing the side-scan sonar images. A revolutionary undersea exploration tool invented by the late Dr. Harold Edgerton, side-scan allowed the quick survey of vast areas of ocean bottom.

A dark vertical line running from the top to the bottom of the screen showed the path of the survey ship. Broad color bands to either side of the line represented the port and starboard areas being probed by the side-scan sonar. Navigational data and time were displayed on the right side of the screen.

Austin stared at the screen, his face bathed in its amber light, alert to every visual nuance. It was a tiring job, and he had been at it for two hours. He had glanced away from the screen and was rubbing his eyes when Zavala and Adler stepped through the door. Zavala was carrying a thermos of coffee and three mugs that he had picked up in the mess hall.

"Coffee break," he said. He poured the mugs full and handed them around.

The hot coffee burned Austin's lips, but it gave him a welcome wake-up lift. "Thanks for the caffeine pick-me-up," he said. "I was getting bleary-eyed."

"I can take the next shift," Zavala volunteered.

"Thanks. I'll put the scan on autopilot for now, and show you and the professor what we've been doing."

Austin set the sonar monitor to buzz if it picked up an object larger than fifty feet in size, and the three men gathered around a chart table.

"We're running a medium-range search to cover the most ground possible without distorting the results," Austin said. "The ocean depth here is about five hundred feet. We've marked out twelve-mile squares along the assumed course of the missing ship." He drew his finger along the perimeter of a rectangle marked in grease pencil on a transparent overlay. "The survey ship follows imaginary parallel lines in each square like someone mowing a lawn. We're about halfway through this square. If we don't locate the ship in this spread, we'll continue to probe a series of overlapping squares."

"Anything interesting turn up?" Zavala said.

Austin made a face. "No mermaids, if that's what you mean. Lots of flat ooze with hard sediment mixed in here and there, boulders, dips and depressions, school fish and sea clutter. No sign of our ship-or any ship, for that matter."

Adler shook his head in frustration. "You wouldn't think it would be so damned difficult with all these electronic gizmos to find a vessel that's longer than two football fields put together."