On his way home from his drab, run-of-the-mill job, drab run-of-the-mill Harry Balbo (Sean Patrick Flanery) is stopped on the corner by a homeless man and asked whether he can spare any change so that he can get something to eat. Harry isn't carrying any change, but he does stop at a convenience store to buy him a hotdog. When he gets back to the corner, the man is nowhere to be seen until the headlights of a passing car show him having his blood drained by a beautiful girl with fangs. She then rips off his head and leaps through a window three stories high. Of course, nobody believes his story--not LAPD Detective Michael Loper (Boyd Kestner), not coworker Chet (Josh Hopkins), and not even Javier (Jon Huertas), the other jerk he works with. The only one who gives some credence to his story is Ronnie Klein (Brad Rowe), the convenience store clerk, but Ronnie has problems of his own. His new chick is so hot for sex that she's draining him of all his energy.The next night, when Harry has trouble sleeping, he wanders out to the crime scene where he sees the chalk outline of the headless victim drawn on the sidewalk and has a feeling that Ronnie might be in danger. He climbs up the fire escape outside Ronnie's apartment and peeks in the bedroom window to see Ronnie having his blood drained by the same girl that ripped off the head of the homeless man. Unfortunately, Harry knocks over a flowerpot, which alerts the girl to his presence. She tears past him, gashing his cheek on the way. The next day, when Harry hears that Ronnie has been found dead, he becomes certain that the girl is a vampire. Searching the internet, he finds a website all about vampires, sends mail to the owner, who calls himself Nightstalker, and asks what to do. Nightstalker says that the only thing he can do is to find the vampire, stake her, and cut off her head. Harry refuses to do that on grounds that it's murder.Turns out that Nightstalker lives in the same apartment building where Harry lives and works part-time doing maintenance, as he finds out when Strickland (Michael Biehn) in 3D calls him to fix a stopped up toilet. Strickland, an L4 quadriplegic, works out of his apartment tracking vampires. He is currently following the whereabouts of nine of them, including the one in Los Angeles. She set up housekeeping in L.A. about two months ago, Strickland explains and shows Harry the map he has made of her known killings and the areas where he thinks she might be resting during the daytime. By searching the tax records for delinquent payments, he has located 12 possible abandoned buildings she could be calling home.Harry decides to try and find the vampire before she finds him. The next day, he calls in sick. Then, armed with the map and an armload of wirecutters, crowbars, sledgehammers, stakes, and a big cleaver, he begins searching through the selected buildings. In the last one, he comes upon the vampire, asleep on the floor. Just as he's about to pound the stake through her chest, she wakes up and pleads with him not to kill her. "I have to eat to live, just like you," she says pitifully, and Harry can't kill her. Instead, he comes up with a plan. He steals a load of steel pipes from his company and builds a cage in the basement of his apartment building. That night, he goes out looking for her. When she sees him, she starts chasing him. Harry runs back into his apartment building, leading her down to the basement and straight into the cage. Before she realizes what's happening, Harry slams the cage shut and locks it.At first, the vampire is enraged. When she calms down, she introduces herself as Tatiana (Charlotte Ayanna) and tries to sweet talk Harry into letting her go free. When Harry refuses, she tells him that he must either feed her or kill her. Harry agrees to feed her. The next day, he brings home a rabbit. She begrudgingly accepts it but suggests that Harry bring home an enemy or, at least, someone he doesn't like. The only person who fits that bill is Javy, the jerk at work that hounds him relentlessly, but Harry refuses.When Strickland finds out that Harry has encaged the vampire rather than killing her, he is livid. He tells Harry the story of how he was paralyzed at 18 years of age when his army troop came upon a village in Vietnam where every man, woman, and child had been wiped out by two vampires...a male and his concubine. It took all their firepower and then a flamethrower to destroy the male, but then his girlfriend showed up and single-handedly wiped out every one of the soldiers in Strickland's unit...with the exception of Strickland. Him she batted just once, breaking his spine. He lay there, pretending to be dead, until a reinforcement troop found him and took him to a hospital after wiping out the female vamp with napalm. Strickland suggests that Harry kill Tatiana now before she overpowers him. He recommends that Harry find himself a new girlfriend. Harry tries to kiss Cindi (Amanda Noret), a girl who lives down the hallway from him, when she brings him a dish of lasagna, but Cindi rebuffs him.Tatiana is having a hard time living on rabbit blood and keeps requesting that Harry bring home Javier for her because she needs human blood. One day, a meter reader comes down in the basement and finds Tatiana in the cage. She begs him to let her out, but he offers only to get the police, so she grabs him through the bars and feeds on him, leaving the body for Harry to dispose of. Realizing that rabbits aren't going to do it for Tatiana, Harry goes online and buys her a pint of human blood and brings it to her on a plate with a red rose, but she tosses it across the room, refusing to drink it because it's dead blood.Poor Harry. He's falling in love with Tatiana. She haunts his dreams and offers to love him back in ways that he can only imagine. Meanwhile, he's making mistakes at work, sending out the wrong flanges, and his theft of the steel pipes has caught up with him. When Chet informs him that Mr Henderson from the main office is coming to see him and Javy starts taunting Harry about how he's going to lose his job, Harry has had it. He confesses to Javy about the insatiable girl he has in his basement and how she needs more lovers than just him. Javier, who thinks of himself as a "sexual Tyrannosaurus" is more than happy to meet Tatiana and eagerly arrives at Harry's apartment decked out with his bag of love toys. At the last minute, however, Harry has a change of heart and tries to talk Javy out of going into the basement. Javy slugs Harry, knocking him out, and grabs the keys.When Javy sees Tatiana, he is aroused and willing to help her satisfy her "appetite". She asks him to get the key on the wall so that he can open the cage. When he comes closer, she begins caressing his arm (the one not holding the keys) until she can control herself no longer and bites down. Harry stumbles down the stairs and tries to pull Javy away from Tatiana, but she rips off his arm, pulls his entire body into the cage, and proceeds to drain him dry.Meanwhile, the body of the meter reader has been uncovered in a plastic bag in the dump, and Detective Loper and his partner have been able to identify the fingerprints on the bag as belonging to Harry Balbo. From the meter reader's meter, they have gotten the address of the last place he visited...Harry's apartment building. After the detectives visit Harry's workplace looking for him, Chet gives Harry a call and warns him that the cops are on the way. Knowing that it's all over, Harry calls Strickland to say goodbye. Then he offers himself to Tatiana, along with the key to her cage. Tatiana is reluctant but finally agrees to turn him. After the deed is done, Harry goes upstairs, knocks on Cindi's door, hands her a rose, and asks to be fed. She invites him in. In the final scene, Strickland waits in his wheelchair facing the front door, a loaded rifle in his hand. "Come on, you motherf****rs," he shouts. "I know you're out there, so come and get me. Come on!"