Bones on Mars - A paranormal, sci-fi, fantasy romance

The mission - colonize the slopes of Olympus Mons on Mars before the Pacific Alliance lands.
The challenge - something isn't quite right with the site foreseen for the colony. Explorations reveal a cave where the support struts for the home dome are supposed to go.
It gets worse - not only does the cave move, but it contains the impossible: a human skeleton. And there's a writing on the wall.
What starts off odd, soon descends into total madness.
But the next shuttle back to Earth doesn't launch until next year.
ONC Prompt 59. The year is 2042. The first astronauts landed on mars. They find a cave with a single human skeleton and four words written on the wall.