And what followed would be much worse: a radioactive plume, riding on the prevailing winds, sickening everyone it came into contact with. Petrov remembered the Chernobyl nuclear reactor meltdown. People were still dying from the effects of radiation poisoning almost two decades later.

Petrov stared at the aluminum face of the device. Its four corners were secured by sunken screws whose heads needed a special tool, which Urmanov had in his tool kit to unloosen them if necessary. Also in the tool kit were instruments that Urmanov would need if there was a problem with the device. Petrov and Gorsky could arm the device without Urmanov, but they were not authorized to remove the face and expose the inner workings of the miniature nuclear bomb.

Ironically, Petrov knew, it was not the plutonium core or even the electronics that presented a problem; it was the two detonator caps and the conventional high explosive charges packed around the plutonium—to compress it and give it the critical mass it needed to achieve fission—that could explode if improperly handled. Thus the age of gunpowder met the nuclear age in this trunk. And Dr. Urmanov, nuclear physicist, had an understanding of both, plus an understanding of advanced electronics if a problem arose.

Mission control had told Petrov that the device had less than a five percent chance of malfunctioning. Urmanov was needed to lower that to zero percent.

If, however, Dr. Urmanov could not seem to solve the problem, then there were ways to help him remember the intricacies of the device he invented.

Petrov again looked at the aluminum face of the device. It had no knobs or dials, no switches or meters, only small, color-coded ports into which electronic leads could be inserted.

The timer clock was internal and not shown in a display window, but would be shown on the handheld arming device that lay in plastic wrap on the surface of the aluminum face.

Petrov picked up the arming device and unwrapped it, letting the four color-coded wires fall free. Except for the dangling wires, this arming device looked like a large satellite phone. And in fact, signals could be sent to Moscow, and also to the nuclear device. He asked Urmanov, “Did you remember to bring your arming device?”

Urmanov reached into his bag and retrieved the backup arming device.

Petrov said, “We will use the one that came with the package.”

He inserted the lead from his black wire into the hole that had a black circle around it. He looked at the electronic display screen on his handheld device and said, “Battery is fully charged and all electronics are reading normal.”

He turned the device toward Urmanov and Gorsky and they both nodded, and both repeated, “Normal.”

He then plugged the green wire into the green port and looked at his display. “Radiation level is within normal range,” meaning there was no radiation leak and no depletion of the plutonium, which was critical if they were to achieve a ten-kiloton yield.

He turned the remote device toward Urmanov. “Correct?”

Urmanov nodded.

The public address speaker crackled and Gleb’s voice filled the garage. “Helicopter across the bow at three hundred meters distance and four hundred meters altitude, proceeding south.” He added, “He has a searchlight, and the beam passed briefly over us.”

Petrov glanced at Gorsky, then said, “If they are looking for the amphibious craft”—he nodded toward the amphibious craft five meters away on the opposite dock—“they would need X-ray vision, like Superman.”

Gorsky smiled, but he was concerned.

Petrov looked at the open trunk. It was now emitting enough radiation to be detected, but it would emit less when the lid was closed, and almost none when it was submerged. But now they were exposed and needed to hurry through the arming sequence. Petrov still did not think that the Americans were thinking the unthinkable. But they might discover this radiation source by accident if they had their detectors turned on and if someone in a helicopter or boat noticed the detector’s flashing red light or somehow heard its audible alert over the sound of their engines.

He said, “We will continue.”

He plugged the yellow wire into the yellow port and a digital calendar appeared on the screen. He set the date for September 12, then switched to clock mode. He pushed the hour button on his control and stopped at 08. He then advanced the minutes to 46.

September 12—08:46. He pressed the Set button and said, “That will be about the time we are over the Atlantic, enjoying our coffee.”

Gorsky nodded, though he was no longer sure they would be on that private jet. But Colonel Petrov seemed sure, as though there were no helicopters flying overhead and no high-speed craft on the sea. Gorsky glanced at Urmanov. Now that this was a minute away from becoming real, Urmanov had become almost catatonic.

Petrov plugged the last wire—the red one—into the last port and said, “We will recite the arming code.” He put his finger on the electronic display that now showed numbers from zero to nine and said, “Seven.”

Gorsky repeated, “Seven.”

Urmanov said, “Seven.”

Petrov pushed seven on the screen, then said, “Three.”

“Three.”

“Three.”

Petrov pressed three, then said, “Nine.”

They went through the eight-digit arming code, until the last number, which was known only to Petrov. He pushed the number, which was zero, and the displayed code disappeared, replaced by the word ARMED.

And, Petrov thought, that was all there was to it. He held up the arming device so that Gorsky and Urmanov could read it, and he said to Urmanov, “So, Doctor, there were no problems and we did not need you after all.”

Urmanov did not reply.

Petrov continued, “You designed a very reliable weapon. I congratulate you.”

Again, Urmanov had no reply.

Petrov unplugged his four lead wires, then took Urmanov’s backup arming device and ran through the procedure again, then said, “I am satisfied.” He looked at Urmanov. “And you?”

Urmanov nodded.

“Good. So we have a hundred percent certainty that nuclear fission will occur tomorrow at zero eight forty-six hours.” He looked at Urmanov. “Correct?”

Urmanov replied, “Nothing is one hundred percent certain.”

“Some things are.” He glanced at Gorsky, who nodded.

Petrov removed the four wires from the nuclear device. Clipped to the underside of the upraised lid was a long coil of copper wire, which Petrov removed. On one end of the wire was a long copper needle, and on the other end was a black rubber ball. Petrov stuck the long needle into a waterproof port on the right side of the trunk, then tossed the ball overboard into the water. This was the external radio antenna, necessary if Petrov needed to send a signal from his arming device to the submerged nuclear device. There were only two signals he might have to send: a shutdown of the timer clock, which he had no intention of sending; or a signal to advance the time of detonation. And that might be a signal he would need to send.

He put his handheld arming device into remote mode and tested the signals sent through the radio antenna. His display screen showed all the data—battery and electronics, radiation, detonation time, and status: ARMED.

Satisfied that he had control of the timer clock, he said to Gorsky, “You may lower the lid.”

“No!”

Petrov and Gorsky turned toward Urmanov, who was standing near the helm of the boat, a gun in his hand. Petrov noticed he was shaking almost uncontrollably.

Gorsky said to Urmanov, “You told me your gun was in your bag. I don’t like people who lie to me.”

Urmanov waved his gun and said in a quavering voice, “Move… away from the trunk.”

Petrov and Gorsky exchanged glances, nodded, and moved toward opposite sides of the lifeboat.

Urmanov took a step forward, pointed his 9mm Makarov at the aluminum face of the nuclear device, and pulled the trigger.