On the planet Lydo, a 19-year-old research student at the Academy named Brad enters the Netherworld to research its little-known inhabitants. The caveat: he will lose his memory and his form.

Waking up in the town of Nofer in Daganland, Brad enters into a world ruled by a Tyrant. It is a planet of darkness where the inhabitants live and work by night. Socialization and friendships are forbidden, except in the formal setting of work-related activities. Brad becomes an elite student, assigned to a graduate program that will lead to his heading the department for incoming immigrants. Humans make up the majority of Daganland's residents, and he is required to observe their habits and behaviors as part of his future career. Instead of obeying his instructors to be merely an invisible observer, he grows fond of the humans, and his studies take a new direction.

In the vein of C. S. Lewis, J. R. R. Tolkien, and William P. Young, Night Rumbles follows Brad as he completes an assignment to research a trio of humans. But as Brad's affection for the humans grows, his conflicted heart forces him to make a decision to yield to his leader's wishes or defy them.

Haunted by an unknown past, and with dangers lurking at every turn, Brad must use all of his cunning to defeat the malicious forces around him and save his new friends. But will he ever get to return to his home world?