With its blend of romance, action, magic and bits and pieces of supernatural hoo-ha imported from other sources – the Potterverse and “Twilight,” most obviously, but also “Star Wars,” “Avatar,” “Lord of the Rings” and the “Blade” and “Underworld” series – this initial “Mortal Instruments” picture has the vibe of a straight-to-video release from the mid-‘90s, except with a $60 million budget and considerable special-effects expertise. Its young stars have the right feeling of almost-famous beauty and anonymity: Lily Collins, who’s had supporting roles in “The Blind Side” and “Stuck in Love,” plays Clary Fray, a New York teenager who discovers that her missing mom has been concealing her true identity, heritage, destiny, etc. Clary’s principal foils are a blond, brooding Anglo Shadowhunter named Jace (Jamie Campbell Bower, who has appeared in both the “Potter” and “Twilight” series) and her mildly nebbishy “mundane” would-be boyfriend, Simon (Robert Sheehan, of the British teen series “Misfits” and the Irish crime series “Love/Hate”). [This is a correction: I previously had this character confused with Alec, played by Kevin Zegers.]

It’s evidently important, in this kind of universe, to present the young female protagonist with sexual dichotomies, as with the choice between the preening, narcissistic Jace, who is liable to play a Bach fugue or kiss her in an enchanted garden at midnight, and the loyal but thoroughly chaste Simon, who at one point gets abducted by vampires and strung up in what looks very much like an S/M bondage club. Jace is like all possible genders at once, Simon none at all. This series also continues the “Twilight” tradition of making parental figures seem inordinately young, thereby suggesting perverse possibilities that may (or may not) be unintentional. In this case, Lena Headey, who plays Clary’s mother (and has lately been seen as Cersei Lannister on “Game of Thrones”), is 15 years older than Lily Collins, although they could easily pass for sisters. Jonathan Rhys Meyers (Henry VIII on “The Tudors”), meanwhile, plays Valentine, a Shadowhunter who has gone to the dark side in some confusing fashion and who may or may not be Clary’s dad, and he’s only about 10 years older than Collins.