After experiencing visions of a nun, author Marie Adams (Romy Windsor) is in the middle of a meeting with her agent, Tom Billings (Antony Hamilton), when she has another vision of a wolf-like creature lunging from a fire, and begins to scream hysterically. Marie’s husband, Richard (Michael T. Weiss), discusses her condition with her doctor, agreeing that Marie’s overactive imagination is leading her into some dangerous territory. The doctor advises Richard to take Marie away from the pressures of her life for a few weeks. Richard locates a cottage in the small town of Drago, some hours from Los Angeles. Tom drives Marie there, but then departs quickly in the face of Richard throwing mad shade. Marie looks around the cottage and declares it to be perfect; but that night, while she and Richard are making love, Marie is disturbed by the sound of howling out in the woods.
After being shuttered for over 500 years following a horrific, intentionally staged family massacre, a mysterious Hungarian castle opens its doors with the apparent intention of attracting tourist business. A diverse group of people from different parts of the globe is assembled at the eerie dwelling after having been chosen when they applied for a visa. But once they arrive some begin to wonder if there is more going on than meets the eye. First they hear terrible stories about savage packs of wolves that used to roam the area and then people begin to disappear, only some of whom are found later with their throats torn out. It soon becomes clear that a murderer is among them, and the culprit may only partially be human.
Ian, a likeable but severely solitary drifter, takes a job making repairs at the local church in the barren rural town of Canton Bluff. Eschewing human contact, Ian seems unnaturally leery of the impending full moon. Aware that Ian is a genuine werewolf, R.B. Harker (the owner of a traveling carnival) captures and forces the young man to work for his carnival, where he is put on display with other human oddities. To further complicate matters, Harker is revealed to have a monstrous secret of his own - he is a vampire.
An Australian man named Ted, intricately connected to the previous three Howling films, arrives in a small western town where he begins to mingle with the local townsfolk, secretly recording his own enigmatic agendas into a tape recorder in his hotel room. At the same time a number of mysterious slayings appearing to be the work of a large animal begin to occur in the area. A detective investigates the case, helped by a priest who is certain the killings are the work of a werewolf, leading the two of them to uncover several clues that connect events from the majority of the latter part of the series.
Tony Rivers (Michael Landon), a troubled teenager at Rockdale High, is known for losing his temper and overreacting. A campus fight between Tony and classmate Jimmy (Tony Marshall) gets the attention of the local police, Det. Donovan (Barney Phillips) in particular. Donovan breaks up the fight and advises Tony to talk with a “psychologist” that works at the local aircraft plant, Dr. Alfred Brandon (Whit Bissell), a practitioner of hypnotherapy.
In 1795, Dr. Victor Frankenstein (Aden Young) creates a monster (Aaron Eckhart), a soulless creature patched together from corpses, and then rejects it, disgusted with what he's made. In a fit of rage, the creature kills Victor's wife Elizabeth (Virginie Le Brun) and Victor chases it to the Arctic to get revenge, but succumbs to the weather. The creature buries his creator in the Frankenstein family crypt and is then attacked by demons before being rescued by the gargoyles Ophir (Mahesh Jadu) and Keziah (Caitlin Stasey), who bring it before the gargoyle queen Leonore (Miranda Otto) and their commander Gideon (Jai Courtney). Leonore explains that they were created by the Archangel Michael to battle demons on Earth and protect humanity. They name the creature "Adam" and invite him to join them, but he declines and departs after being given heavy, baton-like weapons to protect him, as more demons will come after him. The weapons allow him to "descend" demons (destroying their bodies and trapping their souls in Hell) as they have the symbol of the Gargoyle Order carved on them.
Diane suffers from chronic nosebleeds. She checks herself in a mirror and transforms into a monster before falling unconscious. Earlier, she walks in the streets trying to borrow a cellphone in order to call her twin sister Karen. Having no luck, she enters a clothing store and asks to use a phone. There, she meets a girl of her age, Jack, who is clearly smitten by Diane. Diane's nose starts bleeding again and Jack gives her a hand. Jack then takes Diane to a night club. When they get there, Diane seems nauseous, having lost a lot of blood from her nose, and she goes to the restroom. This scene is parallel to the beginning of the film because of the mirror. She gains consciousness, meets up with Jack and the girls passionately kiss.
The film depicts four short stories from Pirandello's 15-volume series Novelle per un anno, which play around his birthplace in the 19th century. A raven, which in the introduction is shown to get a bell around his neck from locals, leads one from one story to the next.
Vernon Coyle (Pasdar), a detective with the Los Angeles Police Department, is trying to solve a series of bizarre murders. His girlfriend, Grace (Polo), turns into a werewolf and is kidnapped by Crispian Grimes (Wise), a vampire and owner of the nightclub, House of Frankenstein.
Darren Shan and his best friend Steve Leonard visit a traveling freak show. Steve believes a performer, Larten Crepsley, is a vampire. Steve talks to Crepsley after the show and asks to become a vampire. Crepsley initially refuses but is talked into testing Steve's blood, that he spits out telling Steve he has bad blood. Steve furiously swears revenge and leaves. Darren overhears everything because he has been hiding in a cupboard after stealing Crepsley's spider, Madam Octa.
When the wealthy count Waldemar Daninsky kills a wolf on his grounds, it transforms into a gypsy upon death, and he finds himself cursed by a vengeful gypsy witch who is angry about him killing one of her band. The witch orders a young, beautiful gypsy girl to seduce Daninsky and then, while he is sleeping, bite him with the skull of a wolf which she smuggles into the count's mansion. When she presses the skull's fangs into his skin, Waldemar becomes a werewolf (without a doubt the most original of all of Waldemar's various "origins" in the series).
The story takes place in 1851 and deals with a small Spanish village apparently plagued by what we would now call a serial killer, as corpses are discovered bearing both savage mutilation and precise surgical incisions. Clues point toward Manuel Romasanta (Julian Sands), who confesses to the crimes, but claims that he is a victim of lycanthropy. A scientist, Professor Philips (David Gant), argues that Romasanta suffers not from a supernatural curse but from a mental disorder.
In the 16th Century, the lycanthrope Waldemar Daninsky goes from his native Europe to Japan, seeking a way to cure himself of being a werewolf. Only a Japanese sorcerer named Kian and a magic silver sword can save him. This film moves the Daninsky family curse back to a medieval setting, as Naschy felt the Daninsky saga need not always be confined to a modern day setting.
In the underground Facility, senior technicians Gary Sitterson and Steve Hadley discuss plans for a mysterious ritual. A similar operation undertaken by their counterparts in Stockholm has just ended in failure.