In the missile-control center - MCC - aft of the cavernous missile room, a senior chief petty officer lit up his panel. All twenty-four birds were on line. On-board navigation equipment fed data into each missile-guidance system. It would be updated in a few minutes from orbiting navigation satellites. To hit a target, the missile had to know not only where the target was, but also where the missile itself was starting from. The NAV-STAR Global Positioning System could do that with a tolerance of less than five meters. The senior chief watched status lights change as missiles were interrogated by his computers and reported their readiness.

Around the submarine, water pressure on the hull diminished at a rate of 2.2 tons per square foot for every 100 feet of rise towards the surface. Maine’s hull expanded slightly as the pressure was relieved, and there was a tiny amount of noise as steel relaxed from the compression.

It was only a groan, scarcely audible even over the sonar systems and seductively close to the call of a whale. Ryskov was so drunk with fatigue that had it come a few minutes later he would have missed it, but though his daydreams were getting the best of him, his mind retained enough of its sharpness to take note of the sound.

"Captain hull-popping noise right there!" His finger stabbed the screen, just at the bottom of the shadow he and Dubinin had been examining. "He's coming shallow."

Dubinin raced into the control room. "Stand by to change depth." He put on a headset that connected him to Lieutenant Ryskov.

"Yevgeniy Nikolay'ch, this must be done well, and done quickly. I will drop below the layer just as the American goes over it "

"No, captain, you can wait. His array will hang below briefly, as ours would do!"

"Damn!" Dubinin almost laughed. "Forgive me, Lieutenant. For that, a bottle of Starka." Which was the best Russian-made vodka.

"My wife and I will drink your health I'm getting an angle reading Estimate target five degrees depression from our array Captain, if I can hold him, the moment we lose him through the layer "

"Yes, a quick range estimate!" It would be crude, but it would be something. Dubinin rasped quick orders to his tracking officer.

"Two degrees hull noises are gone this is very hard to hold, but he's occulting the background a little more now - GONE! He's through the layer now!"

"One, two, three " Dubinin counted. The American must be doing a missile drill, or coming up to receive communications, in any case he'd go to twenty meters depth, and his towed array five hundred meters long speed five knots, and Now!

"Helm, down five degrees on the bow planes. We're going just below the layer. Starpom, make note of outside water temperature. Gently, helm, gently "

Admiral Lunin dipped her bow and slid below the undulating border that marked the difference between relatively warm surface water and colder deep water.