ONCE BITTEN

The Countess, a 400-year-old vampire, has created an army of young male and female vampires who accompany her on her centuries-old journey through eternal life and youth. Though she is immortal, she is required to drink the blood of a male virgin three times by Halloween each year to retain her immortality and her youthful appearance. She finds this task increasingly difficult, since male virgins are nearly impossible to find in the 1980s, particularly in hedonistic cities. With just over a week until Halloween, the Countess sends her vampire minions into Los Angeles to find her a virgin.

Meanwhile, virgin high school student Mark Kendall tries to convince his girlfriend, Robin Pierce, to have sex with him, but she wants her first time to be special. One night, Mark ventures to a singles bar in Hollywood with his best friends Russ and Jamie to try his luck with local women. Once her minions sense Mark's virginity, the Countess lures him to the bar and takes him to her mansion, where she seduces him and bites his thigh, rendering him unconscious. When Mark wakes up with no memory of their encounter, the Countess convinces him that they have had sex. Although he confesses that he has a girlfriend, she asks to see him again before he leaves.

At school, Robin overhears Mark telling Russ and Jamie about how he presumably lost his virginity to another woman, and breaks up with him. Over the next few days, Mark begins exhibiting strange behavior, such as avoiding direct sunlight and drinking blood from raw meat, and dreams that the Countess sucks his blood. Mark eventually reconciles with Robin, and while visiting her at the clothing store where she works, he is surprised by the Countess in the fitting room. After Mark rejects the Countess's advances, she bites him a second time and leaves.

As Mark and Robin dance at the school's Halloween dance, the Countess arrives and interrupts them. The women then have a dance-off, and the Countess leaves defeated. Afterward, Mark tells Robin that he believes the Countess is turning him into a vampire, before they both notice that he has no reflection in the mirror. While seeking information about vampires from a bookseller, Robin learns that, to drain the blood of a male virgin, female vampires bite their victims in the inner thigh.

One evening, the Countess kidnaps Robin to lure Mark to her mansion for the final bite. With Russ and Jamie in tow, Mark finds and frees Robin in the Countess's basement, and Robin informs Mark that the Countess did not have sex with him and only drained his blood. The four teenagers are soon captured, and Mark is strapped to a chair as the Countess prepares to bite him a third time. After Robin, Russ, and Jamie manage to free Mark, Robin flees with him through the mansion while being chased by the Countess's minions. Meanwhile, Russ and Jamie are seduced by two of the Countess's female minions.

Shortly after Mark and Robin discover a room filled with coffins, the Countess arrives to find the couple having sex inside a large coffin, rendering Mark's blood useless to her. As the clock strikes midnight, the Countess rapidly ages before their eyes, turning into an elderly woman. Her manservant, Sebastian, assures her that there are other virgins in the world, though the Countess doubts she will find another virgin. Mark and Robin continue to have sex in the coffin.

Mark and Robin are pursued by the Countess and her minions through the mansion, culminating in a confrontation that resolves Mark's fate and the Countess's quest for eternal youth.

The film's ending plays out as a battle of wits and willpower, with Mark and Robin overcoming the Countess's supernatural advances. It satirizes both horror conventions and teen anxieties about sex and adulthood. Ultimately, the resolution underscores the power of genuine connection over predatory allure, leaving the Countess thwarted in her pursuit of eternal youth.