But the Stars

"But the stars that marked our starting fall away.
We must go deeper into greater pain,
for it is not permitted that we stay."

Dante Alighieri, Inferno, 1301 AD

At the start of the 22nd century, the starship Acheron is in orbit around WISE 5571 only, unbeknownst to the crew, the ship has been overrun by telepathic extraterrestrials. How do you fight an enemy that distorts everything you see? What do you do when you can't trust your own senses, let alone anyone around you?