"You bet, sir," Sonarman 1/c Laval said, reaching up to tap the tape machine. A new cassette was taking all this in, and another video system was recording the display on the waterfall screens. "There go the motors, just increased speed. Aspect change…it's got us, zero aspect on the fish, screw noises just faded." Meaning that the engine noise of the torpedo was now somewhat blocked by the body of the weapon. It was headed straight in. Kennedy turned his head to the tracking party. "Range to fish?"

"Under two thousand, sir, closing fast now, estimate torpedo speed sixty knots."

"Two minutes to overtake at this speed."

"Look at this, sir." Laval tapped the waterfall display. It showed the track of the torpedo, and also showed the lingering noise of the decoy, still generating bubbles. The Type 89 had drilled right through the center of it.

"What was that?" Laval asked the screen. A large low-frequency noise had just registered on the screen, bearing three-zero-five. "Sounded like an explosion, way off, that was a CZ signal, not direct path." A convergence-zone signal meant that it was a long way away, more than thirty miles. Kennedy's blood turned a little cold at that piece of news. He stuck his head back into the attack center. "Where are Charlotte and the other Japanese sub?"

"Northwest, sir, sixty or seventy miles."

"All ahead flank!" That order just happened automatically. Not even Kennedy knew why he'd given it.

"All ahead flank, aye," the helmsman acknowledged, turning the annunciator dial. These exercises sure were exciting stuff. Before the engine order was acknowledged, the skipper was on his command phone again: "Five-inch room, launch two, now-now-now!"

The ultrasonic targeting sonar on a homing torpedo is too high in frequency to be heard by the human ear. Kennedy knew that the energy was hitting his submarine, reflecting off the emptiness within, because the sonar waves stopped at the steel-air boundary, bouncing backward to the emitter that generated them.

It couldn't be happening. If it were, others would have noted it, wouldn't they? He looked around. The crew was at battle stations. All watertight doors were closed and dogged down as they would be in combat. Kurushio had launched an exercise torpedo, identical to a warshot in everything but the warhead, for which an instrument package was substituted. They were also designed not to hit their targets, but to turn away from them, because a metal-to-metal strike could break things, and fixing those things could be expensive.

"It's still got us, sir."