Valentine is a 2001 slasher film directed by Jamie Blanks and starring Denise Richards, David Boreanaz, Marley Shelton, Jessica Capshaw, and Katherine Heigl. Loosely based on the novel of the same name by Tom Savage, the film follows a group of women in San Francisco who are stalked by a killer wearing a Cupid mask.
At a junior high school St. Valentine's Day dance in 1988 San Francisco, Jeremy Melton, an outcast student, asks four popular girls to dance. The first three girls, Shelley Fisher, Lily Voight, and Paige Prescott reject him spitefully and cruelly, while the fourth girl, Kate Davies, politely responds "maybe later". Their overweight friend Dorothy Wheeler accepts Jeremy's invitation and they proceed to secretly make out underneath the bleachers. When the school bully Joe Tulga and his friends discover them, Dorothy claims that Jeremy sexually assaulted her. Joe and his friends publicly strip and severely beat Jeremy, and his nose starts bleeding under the distress. It is later revealed Jeremy was expelled and eventually transferred to reform school and juvenile hall, due to Lily, Paige, Shelly and Joe testifying against him for unwanted sexual advances towards Dorothy and then ended up in a state-run mental institution.
Thirteen years later, in 2001, Shelley, now a medical student at UCLA, is at the morgue one evening studying for her medical exam. After receiving a vulgar Valentine's card in her locker, she is attacked by someone in a trench coat and Cupid mask. She is cornered in a cooler used to store cadavers, where she attempts to hide in a body bag, but the killer finds her before slitting her throat. The killer's nose bleeds as she dies.
At Shelley's funeral, Kate, Lily, Paige, and Dorothy are questioned. They admit to not having seen her in some time after she moved from San Francisco to Los Angeles. Paige, Lily and Dorothy subsequently receive obscene cards, each signed "JM." Lily's card came with a box of chocolates which she finds are filled with maggots. Meanwhile, Dorothy's boyfriend, Campbell, loses his apartment and temporarily moves in with her at her father's large mansion.
As the girls attend the exhibit of Lily's artist boyfriend Max, they meet Campbell's bitter ex-girlfriend Ruthie, who accuses him of being a con artist. Lily becomes lost at the exhibit and the killer appears, who proceeds to shoot her repeatedly with arrows until she falls several floors into a dumpster. When they have not heard from Lily, the others assume she is in Los Angeles on a work trip. Upon contacting the police, they agree that the culprit can be Jeremy Melton. Dorothy admits to Kate & Paige that she lied to avoid being humiliated and that Jeremy never attacked her; ruining his life by causing him to be beaten and sent to reform school. Meanwhile, Kate's neighbor Gary breaks into her apartment to steal her underwear. The killer catches Gary in the act and hits him with a hot iron, then proceeds to brutally beat him to death with the object.
As Valentine's Day approaches, Dorothy is planning a party at her family's estate. On the morning of the party, the killer murders Campbell with an ax in the basement. The others assume he has simply left Dorothy, angering her, to which Dorothy believes that they are jealous and still look at her as the "fat girl" of the group. After coming to the party to confront Dorothy with the truth about Campbell, Ruthie is thrown through a shower window by the killer who then impales her neck on the glass. At the party, Paige is attacked and trapped in a hot tub by the killer. The killer impales her in the shoulder with an electric drill before throwing it into the water, electrocuting her.
The party disintegrates when the power cuts out, and Dorothy and Kate argue over who the killer is. Kate claims that Campbell could be a suspect because they do not know anything about him or where he is, while Dorothy counters by accusing Adam, Kate's recovering alcoholic on-off boyfriend, who is now a journalist. After being told by Lily's boyfriend that she did not arrive in Los Angeles as planned, Kate realizes she is also probably dead and calls Detective Vaughn who was assigned to the case. After dialing the number, she follows the sound of a ringtone outside the house and discovers Vaughn's severed head in the pond.
Kate becomes convinced that Adam is actually Jeremy, disguised by reconstructive surgery, and goes back into the house, only to find Adam waiting for her. To her surprise, he asks her to dance. Kate becomes frightened, knees him in the groin and flees. She runs through the house, discovering Dorothy's room trashed and Paige and Ruthie's corpses. She locates a gun, but the Cupid masked killer jumps out from the darkness and sends them both tumbling down a staircase. The killer arises and is shot to death by Adam. As a shocked and confused Kate apologizes profusely, Adam pulls off the mask to reveal Dorothy. Adam forgives Kate, explaining that childhood trauma can lead to lifelong anger and some people are eventually forced to act on that anger, referring to Dorothy. As Kate and Adam wait for the police to arrive, they hug and Adam says he has always loved her. Moments later, when Kate closes her eyes, Adam's nose begins to bleed, revealing that he is in fact Jeremy Melton and the true killer, framing the dead Dorothy for his crimes as she did to him 13 years prior.