Complex sentence: After a reclusive soujourn on Mars where little record of his activity is publicly known, he returned to the world of science fiction with "Orlando's Third Trance" in the closing hours of last century.
Split into simpler sentences: After a reclusive soujourn on Mars where little record of his activity is publicly known. He returned to the world of science fiction with "Orlando's Third Trance" in the closing hours of last century.