The Weapon Makers A. E. van Vogt 1979
The story of Captain Hedrock, Earth's immortal man-up against one force-the outlawed Weapon Makers-who could make that immortality end abruptly if they could but find him. In the world of the lsher Empire a titanic struggle is taking place.
An interstellar drive has been perfected; and the Empress Isher, convinced that it will be ruinous to her government, and that emigration to the stars will strip the solar system of its inhabitants, is using all her power to suppress the invention.
The Weapon Makers, a unique organization, outlawed, but maintaining its freedom by means of secret inventions, is striving with equal determination to force the stellar drive into the open.