The first few hours they had trailed this contact, Mancuso had been careful to keep his distance. He had learned that the submarine was not turning quickly. She was, rather, maneuvering in a leisurely manner, and seemed to ascend fifty to eighty feet as she turned, banking almost like an aircraft. He suspected that the Russian skipper was not using his full maneuverability—an intelligent thing for a captain to do, keeping some of his performance in reserve as a surprise. These facts allowed the Dallas to trail very closely indeed and gave Mancuso a chance to chop his speed and drift forward so that he barely avoided the Russian's stern. He was getting good at it—a little too good, his officers were whispering. The last time they had not missed the Russian's screws by more than a hundred fifty yards. The contact's large turning circle was taking her completely around the Dallas as the latter sniffed at her prey's trail.

Avoiding collision was the most dangerous part of the maneuver, but not the only part. The Dallas also had to remain invisible to her quarry's passive sonar systems. For her to do so the engineers had to cut power in their S6G reactor to a tiny fraction of its total output. Fortunately the reactor was able to run on such low power without the use of a coolant pump, since coolant could be transferred by normal convection circulation. In addition, a strict silent ship routine was enforced. No activity on the Dallas that might generate noise was permitted, and the crew took it seriously enough that even ordinary conversations in the mess were muted.

"Speed coming down," Lieutenant Goodman reported. Mancuso decided that the Dallas would not be part of a ramming this time and went aft to sonar.

"Target is still turning right," Jones reported quietly. "Ought to be clear now. Distance to the stern, maybe two hundred yards, maybe a shade less . . .Yeah, we're clear now, bearing is changing more rapidly. Speed and engine noises are constant. A slow turn to the right." Jones caught the captain out of the corner of his eye and turned to hazard an observation. "Skipper, this guy is real confident in himself. I mean, real confident."

"Explain," Mancuso said, figuring he knew the answer.

"Cap'n, he's not chopping speed the way we do, and we turn a lot sharper than this. It's almost like—like he's doing this out of habit, y'know? Like he's in a hurry to get somewhere, and really doesn't think anybody can track—wait . . .Yeah, okay, he's just about reversed course now, bearing off the starboard bow, say half a mile . . .Still doing the slow turn. He'll go right around us again. Sir, if he knows anybody's back here, he's playing it awful cool. What do you think, Frenchie?"