Convergent Series (Heritage Universe, #1-2)

Hans Rebka intends to solve the galaxy's most persistent mystery. He is going to penetrate Paradox. Many have entered Paradox before Hans Rebka, but no one has ever left, at least not with mind intact. But as a troubleshooter, Hans Rebka is in a class by himself, though he doesn't know it, he's about to uncover the secret of the Artifacts--and loose the most hideous menace ever encountered. Renowned troubleshooter Hans Rebka vows to penetrate Paradox, a mysterious structure left by a powerful and ancient race, from which no one has survived intact and which harbors the galaxy's most terrible menace. Reissue.