Gateway

From the back of the box The gamble is the same for every Gateway prospector. You strap yourself into an alien starship whose destination was programmed 500,000 years ago by a race called the Heechee. You may return with a motherlode of technology that will make you rich. More likely, you will die. But when scientists discover the terrible secret behind the vanished Heechee civilization, you enter a desperate battle against an ancient race so ruthless and deadly that they are known simply as The Assassins.