Nathan felt as if he had been slapped suddenly with a giant pillow that pressed him flat in the chair. The acceleration of the _Corsair_ was greater than any he had experienced before, and his father's old ship had never been equipped with inertia chairs. He caught no glimpse of the edge of the cavern's maw as the ship passed upward through it. One instant they were in the cave, the next they were in the sky and only seconds passed until they were soaring above the thick cloud layer of Venus. After five minutes of such intense acceleration, the Firebird relaxed and cut the controls to a point where they could breathe more easily. "Why the hurry?" Nathan gasped. "Nobody is chasing us!" Firebird made no answer. She reached towards the small panel at the lower edge of the control board and switched on the viewing plate. Silently, she scanned the heavens behind them and the surface of the planet they were leaving. The focus of the plate extended and retreated, then suddenly it concentrated upon a blunt-nosed black vessel rising somewhere below them. "The Black Warrior," said Firebird. "He was watching for us to leave." * * * * * Nathan watched the black ship for hours while Firebird guided the _Corsair_. Steadily the strange vessel gained on them. "We could outrun him easily," said Firebird, "if it weren't for that bad motor. Do you know how to handle light cruiser lances?" "My father never carried a gun on his ship in his life." "I remember," said Firebird. "How I used to argue with him. He said he wouldn't risk being caught by the police in an armed vessel, so he never came aboard the _Corsair_." "Perhaps a wiser man than his son," said Nathan. He told himself he wanted no part of this. He was an engineer, not a buccaneer. Yet as the black vessel approached he felt the thrill of its challenge. The challenge of combat in the impersonal depths of space. His father had felt that challenge--the challenge of men and of space itself, and he had met it with his own bare hands. It was impossible for Nathan not to feel it. They kept their steady pace at an acceleration something more than fifteen G's. Firebird gave Nathan brief instructions in the operation of the weapons and controls. A viewing screen provided Nathan with sights. Its scale automatically corrected for the relative motions of the two vessels. Abruptly, and without warning, the Black Warrior fired. The _Corsair's_ defensive screens caught the blast with an absorption of energy that made the dissipators whine and grow incandescent. "He's using high powered stuff," said Nathan. "Those screens can't take much of that." "They weren't meant to. The _Corsair's_ main defense is her speed. There wasn't room for heavy screens. This time our defense has to be better shooting. Watch this."