The film begins with a late-shift worker laboring in the dimly lit basement of a textile factory, where he is seen feeding bales of cotton into a large industrial machine. During a moment of frustration sparked by the sweltering heat—revealed by a thermometer reading over 100 degrees—he slams his fist against a support beam. This careless action drives a rusty nail into his hand, prompting him to treat the injury with anti-bacterial ointment and gauze from a nearby medical cabinet. As he finds solace in his break, he notices a gathering of rats observing him. Driven by a mix of anger and bravado, he begins to taunt the rodents, ultimately throwing one into the industrial machine. The gruesome scene unfolds as we witness the rat being shredded, leaving a scarlet stain on the cotton. With the rats watching intently, a looming shadow brings terror; the worker stumbles backward into the machine, meeting a horrific end as his remains are consumed by the very rats he had tormented.
The following day, an exterminator, played by Brad Dourif, ascends to the roof of an industrial building with a fire hose in tow. He inserts the end of the hose into the ventilation pipe while a man beneath waits by a pump motor, eager for the exterminator to prepare. Once set up, the exterminator signals his partner, who cranks the pump motor, initiating a flow of water into the building that vacuums out the rats infesting the premises, releasing them into the nearby stream.
Amidst these events, a drifter named John Hall, portrayed by David Andrews, arrives in a small town in search of work. He applies at the local textile company, the town’s primary employer, where foreman Warwick, played by Stephen Macht, begrudgingly agrees to hire him after making degrading comments about his drifter lifestyle and college education. John is coerced into accepting minimum wage for the initial four weeks and is assigned the dreaded "Graveyard Shift" from 11 PM to 7 AM.
As Warwick navigates his own troubles with a building inspector threatening to shut down operations due to a rampant rat issue, he resorts to bribery, offering the inspector $200 to postpone his report until after the 4th of July. The foreman hastily sends employees to the basement to string lights before the clean-up, but one by one, they fall prey to an unknown creature lurking in the dark, with a tide of rats heralding each gruesome encounter. Their disappearance goes unnoticed, and a "Now Hiring" sign is posted.
With the holiday approaching, Warwick informs employees of the closure. Union workers will receive holiday pay while non-union workers face a week-long layoff unless they opt to help with the clean-up and earn double pay. This leads to six workers, including John, being assigned to the task. One fateful night, John discovers a trap door leading deeper beneath the building. As they venture down, the stairs collapse, trapping the group with the menacing creature. Panic ensues as the monster picks them off one by one, leading to escalating tension among the survivors. In a final confrontation, Warwick's desperation to maintain his façade culminates in his demise, leaving only John and Warwick struggling against the beast.
In a dramatic showdown at the industrial machine, John faces the monstrous bat that has haunted them, culminating in a fierce battle that sees him turning on the machine, resulting in its grisly end. The tension finally breaks as John breathes a sigh of relief, escaping the nightmare.
The film concludes with a scene showcasing the textile mill now operating “under new management,” leaving viewers with a chilling hint of the dark events that transpired. As the credits roll, the haunting story of survival and the consequences of neglect come to an unsettling close.
