The compass swung around, the only indication to anyone on board the Toledo that the boat was turning. The indicator steadied up with the arrow pointing at “one-eight-zero,” due south. Now they would have to hang on for the array to stabilize behind them, five minutes of anxious waiting. There was nothing to do but hope the target would still be discernible. It was a time that tried men’s patience. It was a game that required slow, stealthy stalking of the prey. Nothing like high-speed, high-adrenaline air battles, with everything decided in a few terrifying seconds. This was more like the slow, deliberate tracking of a big-game hunter. Find the prey, sneak up on him, and shoot him before he even knew anyone was there. Otherwise, the hunter could become the hunted.

Edwards held his headphone close to his ear, concentrating on what he was hearing. He held his hand up, signaling silence. “Sonar reports regain of sierra three-one, bearing zero-three-two. Drop sierra three-two, track sierra three-one.”

They were back in business. The other submarine had not gotten away. They had verified that the target to the northeast was the real one.

Edwards stood next to Glass once more. He slid the headphone back off his ear, easing the pressure a little.

“How do you think everyone is doing, Captain?” he asked.

The XO was aware that this was Glass’s first time to evaluate the team under pressure. He was hoping to make a good impression. “Okay so far. We’ll see how it goes.”

Hunting a submarine with another submarine was a competition played out entirely in the dark. The hunter listened for the other guy and tried to determine where the quarry was located and where he was going. The only real information to work with was the bearing and the received frequency of the sound—range, speed, and course had to be inferred from those two snippets. The usual game plan was to be quiet and listen a little, try to determine how the bearing and frequency were changing, change course accordingly, and then do it all over again. After several iterations of checking all possible answers and discarding the wrong ones, the only answer left would be the correct one.

This all depended on the target cooperating by staying on the same course at the same speed. Otherwise, it meant starting all over again or losing the game.

“Master Chief Zillich reports he is starting to get hints of some other tonal lines showing up,” Edwards said. “Nothing definite yet, but looks like it could be our guy, very distant.”

Glass nodded. Ever since he first received his orders to command, he had heard stories of Tommy Zillich and his legendary exploits with a sonar system. The crew viewed his abilities as mystical. If Master Chief said there was a flying saucer out there full of little green men, you could break out the Martian dictionary.