"A ring?" Susan looked doubtful. "Tankado's missing a ring?"

"Yes. We're lucky David caught it. It was a real heads-up play."

"But you're after a pass-key, not jewelry."

"I know," Strathmore said, "but I think they might be one and the same."

Susan looked lost.

"It's a long story."

She motioned to the tracer on her screen. "I'm not going anywhere."

Strathmore sighed heavily and began pacing. "Apparently, there were witnesses to Tankado's death. According to the officer at the morgue, a Canadian tourist called the Guardia this morning in a panic-he said a Japanese man was having a heart attack in the park. When the officer arrived, he found Tankado dead and the Canadian there with him, so he radioed the paramedics. While the paramedics took Tankado's body to the morgue, the officer tried to get the Canadian to tell him what happened. All the old guy did was babble about some ring Tankado had given away right before he died."

Susan eyed him skeptically. "Tankado gave away a ring?"

"Yeah. Apparently he forced it in this old guy's face-like he was begging him to take it. Sounds like the old guy got a close look at it." Strathmore stopped pacing and turned. "He said the ring was engraved-with some sort of lettering."

"Lettering?"

"Yes, and according to him, it wasn't English." Strathmore raised his eyebrows expectantly.

"Japanese?"

Strathmore shook his head. "My first thought too. But get this-the Canadian complained that the letters didn't spell anything. Japanese characters could never be confused with our Roman lettering. He said the engraving looked like a cat had gotten loose on a typewriter."

Susan laughed. "Commander, you don't really think-"

Strathmore cut her off. "Susan, it's crystal clear. Tankado engraved the Digital Fortress pass-key on his ring. Gold is durable. Whether he's sleeping, showering, eating-the pass-key would always be with him, ready at a moment's notice for instant publication."

Susan looked dubious. "On his finger? In the open like that?"

"Why not? Spain isn't exactly the encryption capital of the world. Nobody would have any idea what the letters meant. Besides, if the key is a standard sixty-four-bit-even in broad daylight, nobody could possibly read and memorize all sixty-four characters."

Susan looked perplexed. "And Tankado gave this ring to a total stranger moments before he died? Why?"

Strathmore's gaze narrowed. "Why do you think?"

It took Susan only a moment before it clicked. Her eyes widened.

Strathmore nodded. "Tankado was trying to get rid of it. He thought we'd killed him. He felt himself dying and logically assumed we were responsible. The timing was too coincidental. He figured we'd gotten to him, poison or something, a slow-acting cardiac arrestor. He knew the only way we'd dare kill him is if we'd found North Dakota."

Susan felt a chill. "Of course," she whispered. "Tankado thought that we neutralized his insurance policy so we could remove him too."

It was all coming clear to Susan. The timing of the heart attack was so fortunate for the NSA that Tankado had assumed the NSA was responsible. His final instinct was revenge. Ensei gave away his ring as a last-ditch effort to publish the pass-key. Now, incredibly, some unsuspecting Canadian tourist held the key to the most powerful encryption algorithm in history.

Susan sucked in a deep breath and asked the inevitable question. "So where is the Canadian now?"

Strathmore frowned. "That's the problem."

"The officer doesn't know where he is?"

"No. The Canadian's story was so absurd that the officer figured he was either in shock or senile. So he put the old guy on the back of his motorcycle to take him back to his hotel. But the Canadian didn't know enough to hang on; he fell off before they'd gone three feet-cracked his head and broke his wrist."

"What!" Susan choked.

"The officer wanted to take him to a hospital, but the Canadian was furious-said he'd walk back to Canada before he'd get on the motorcycle again. So all the officer could do was walk him to a small public clinic near the park. He left him there to get checked out."

Susan frowned. "I assume there's no need to ask where David is headed."