A man called Vincent (Phil Fondacaro) and his associates are exploring a forest, until they find a cave containing a coffin with the skeleton of Lilith, the mother of all vampires. Vincent takes a box out of his pocket, which contains the four sections of Lilith's heart. He puts it in her body, and she rapidly begins reanimating. After coming back to life, she rips the hearts out of the associates and goes after Vincent, who produces the key artifact seen in Demon Knight. Lilith promises to Vincent that if she can have the last man in the room to eat, she will behave for him. Vincent complies.

The Cryptkeeper is having lunch with the Mummy (William Sadler), who is boring the Cryptkeeper about his life in the film industry. The Mummy challenges the Crypt Keeper to a contest of rock, paper, scissors which the Mummy wins, and he slices off the Keeper's hand with a meat cleaver. The Cryptkeeper laughs (as it didn't hurt him at all) and the Mummy gets ready for the next round. The Cryptkeeper addresses the audience, and the movie continues.

Katherine (Erika Eleniak) lives with her delinquent brother Caleb (Corey Feldman). He goes out one night against her wishes and, while hanging at a bar, is informed of a secret brothel in the guise of a funeral home. Caleb and a friend go to check it out where they do indeed find the information true (albeit forced on them by the funeral home keeper, McCucthion (Aubrey Morris)). Unknown to them however, the place is run by the fully rejuvenated Lilith. All of the women working there are vampires, turned by Lilith (a few still have bite marks on their necks) completely evil, lustful and subservient to her who uses them for both business as well as to lure men to them for food. The boys take different girls for a private session in which Lilith visits them both as the prostitutes prepare to drain their blood. Caleb's friend is killed when Lilith kisses him and extends her tongue down his throat to push his heart out of his body. She promptly rips it out and eats it afterwards. Lilith then sets her sights on Caleb just as he notices his prostitute has bite marks on her neck. As he meets Lilth who offers a three-way, the screen fades to black as she growls ominously.

It soon cuts to a week since then as Katherine visits the police to ask them to look for him, to no avail. Katherine reluctantly hires Rafe Guttman (Dennis Miller), a cynical and sarcastic private investigator whose office is an old adult movie theater, to look for Caleb. After getting some clues via the church where Katherine, and coincidentally Vincent, works and meeting her boss, the Revered J.C. Current (Chris Sarandon). Rafe manages to track down Caleb's trail to the bar where he is directed to the funeral home. He is denied access the first time as the brothel is closed for the night. He sneaks in and uncovers that the money from the clients that visit the brothel is put towards a major Christian organization which is being used as a front for their shady dealings. He also passes by Lilith interviewing a woman whom Vincent recommended to for a job. At first Rafe dismisses it as nothing but as he continues snooping, he hears the woman scream followed by a body hitting the floor but has to leave before he can look into it.

On his second visit, Rafe manages to get into the brothel on a night its open and is given to Tallulah (or Tammy as Rafe calls her) the woman from before, only now much more seductive then what was seen when she was being interviewed, an obvious sign she's been turned. He escapes her by strapping her to a torture rack and investigating the funeral home further, finding a dead servant of Lilith's in the process, before fleeing the grounds. However, he dropped his wallet while doing so, allowing Lilith to find his address. Having tasted some of Rafe's blood that Tammy managed to scratch off, Lilith takes an interest in Rafe and tries to seduce him, but he is unswayed by her sexual advances. Its at that moment Katherine comes by to check on his progress. She leaves when she thinks he's flirting but he tells her of the brothel's activity. They confront Lilith and Vincent over it; however, when they get the police to look over the grounds, all the evidence has been covered up and Rafe is dismissed as a fraud. Meanwhile, Vincent destroys the key so Lilith is now immortal.

As Katherine is looking over some footage shot at the club where they confronted Lilith, she notices that Lilith isn't in the shot. Realizing that Rafe might be right, she calls him over to look over the tape as well. No sooner then he meets her, they get a call from Caleb pleading for help.

Going by his directions, the two track the call to a factory and head inside where they find Caleb on the ground. Rafe, however, is wary and goes to check on him first. His instincts prove right as, unsurprisingly, Caleb reveals he's now a vampire, having been spared having his heart eaten in exchange for undead servitude to Lilith. Rafe and Katherine try to escape but Rafe, in trying to swing across a gap, swings too far and out a window, landing on the police chief's car. Katherine, who took a ladder down, is caught by Caleb, Vincent and McCutcheon, brought back to the brothel and into Lilith's clutches.

Rafe awaken in a hospital but strapped down to be taken into custody once he's healed. Rafe manages to break free just as Tammy, posing as a nurse, arrives to kill him. However Rafe manages to pushes her into a window where her back is exposed to sunlight, causing her undead body to explode. As night falls, Lilith awakens to feed on Katherine to bring her into her undead horde. Katherine pleads for Caleb to help, but he's clearly beyond the point of humanity telling his sister that being a vampire "is pretty damn cool."

Rafe loads up on Super Soakers filled with holy water and raids the brothel, killing Vincent and McCutcheon. He meets up with Current, who realized his wrongdoing and wishes to make amends (Rafe luckily saving him from Vincent who had turned on him). Rafe gives him a spare water gun and the two enter the brothel, spraying all the vampires who burn and explode on contact with the water. They split up to find Katherine, Caleb attacks Rafe with an axe but Rafe kills him by spraying his midsection, burning a hole through his undead body.

Current finds Katherine but it turns to out to be Lilith in disguise. He tries to stake her but she easily stops his attack, breaks his hand and kills him with his own knife. Rafe arrives shortly after and manages to cut into Lilith's body with an axe. It does some damage but doesn't kill her. She reattaches her body before fleeing while Rafe finds the real Katherine and they tend to Current, who dies from his wounds.

Rafe and Katherine head to the church to reveal the existence of vampires via the church's media equipment. Lilith returns, leaving a bloody trail as she confronts the two. She handcuffs Rafe to a railing before going after Katherine who's no match for her inhuman strength. Rafe uses a nearby laser machine (used in Current's sermons) to aim and hit Lilith in the heart, cutting it into four parts, (as splitting her heart is the only thing that can stop her and the machine conveniently makes cross-shaped cuts). However as the heart pieces need to be out of her body, Lilith remains alive. She turns her attention to Rafe, devolving into a much more hideous form. Just as she's about to be kill him, Katherine grabs a candle stand and stabs Lilith's heart out from behind. Lilith's body burns as a result before collapsing to the ground, dead for good.

The next day, the two have Lilith's remains burned to prevent her from returning and lock away the box with the heart pieces in it. As Rafe and Katherine sit in Rafe's car. Rafe begins to fondle Katherine which she oddly seems more accepting of now, when he asks "What's that perfume you're wearing?" He pulls back her skirt to find a pair of bite-marks on her thigh, where she was presumably bitten by Lilith. Katherine replies, "It's not perfume. It's sunblock." Rafe realizes in horror that she has become a vampire, having been undead since her rescue. Katherine, dropping all pretense of her former self, reveals her fangs, grabs and bites into him. Ensuring that even with Lilith dead, her legacy will continue.

Where go back to the Cryptkeeper, where he jokes that if Rafe and Kathy got married, she'd know "what's eating him; her". He has also apparently bested the Mummy at the game and reduced him to nothing but a head. The Cryptkeeper tells him to "quit while he's "ahead"" before laughing, ending the movie.