"The Path Beyond the Stars" is a 1969 science-fiction novel by Emil Petaja. It begins as a standard "space empire" work of science-fiction, but quickly shifts to be an alternate history with fantasy overtones.

The fate of the Universe was in his hands as he battled Trog the Destroyer
It say on the front cover, and if that leads you to believe that this is some form of pulp, you are probably right. A book with "Trog the Destroyer" is probably not some type of new wave experimental sociopolitical piece. Jon Wood lives around San Francisco, California, where he works as a "star dowser"--- he has powers that let him know what stars have habitable planets. Which, he will explain, is nothing weird or mystical, but just scientifically sound ESP. In a twist on the "damsel in distress" plot that begins detective novels, a beautiful woman named Venus Trine comes to his office, and tells him that she is in a space cult of astrologers who are being persecuted by an extradimensional entity called "Trog", and that Jon, as someone who was found in a space lifeboat (kind of like Superman, he was ejected in a life-support capsule into space), has no star chart and therefore is the only one who can defeat Trog. After Venus disappears, Jon psychically sends his mind back in time, where in ancient Babylon he finds Venus in the body of the daughter of the prophet Ezekiel, whose visions were, of course, about UFOs. He then hops through time, visiting Stonehenge and meeting Nostradamus, all on the trail of the mysterious Trog, who exists outside of the pattern created by an astrology that takes in every star in the galaxy. And when the body-and-era hopping Jon and Venus finally meet with the fearsome Trog---they might have one final twist waiting for them.

This is the fifth book I've read by Emil Petaja, and my opinion has shifted with each book. Rather than coherent "world building", his books engage in as many concepts as possible, involving science-fiction and mythology. Sometimes these concepts come together to form a story that feels unified, and sometimes, as in this book or Doom of the Green Planet, it feels disjointed. It isn't a terrible result, because it still felt like an interesting book, and I read it in a few days, but it didn't quite gel into a story that felt as meaningful as its seemingly galaxy-spanning nature would have it.