John Hall, a drifter looking for work, finds employment at a decrepit textile mill in a small town. The factory is managed by the tyrannical Warwick, who assigns Hall to the night shift, during which the crew is tasked with cleaning out the building's basement that is infested with rats. As Hall and his co-workers delve deeper into the mill's bowels, they begin to uncover a series of mysterious deaths among former employees that have been kept under wraps. Despite the unnerving atmosphere, Hall forms a bond with Jane Wisconsky, another worker under Warwick's oppressive thumb.

As the night progresses, the situation becomes more perilous when they stumble upon a hidden sub-basement laden with an unfathomable horror. The group faces mounting dread as they realize they're contending with a far more sinister force lurking in the dark. The dire conditions underground push everyone to their limits, forcing them to confront both the external threats and their own personal demons. As tensions heighten and dangers to their survival increase, the workers fight to escape with their lives while uncovering the grim history buried within the mill's labyrinth.