The Mortal Instruments: City of Bones

So, imagine that Twilight and Harry Potter got drunk together one night, lost all inhibitions and ended up falling foolishly into the same bed. Nine months later, we might be presented with something a little like this unfortunate aberration.

Well, we would if Twilight and Harry Potter were first cousins. The Mortal Instruments: City of Bones is such a pathetic mess you end up feeling a little sorry for the poor mite. It doesn't deserve our hatred. It deserves to be wrapped up in a blanket and placed in front of the TV.

As you will have guessed, the story concerns a young person who discovers that, despite feeling ordinarily ordinary all her life, she is, in fact, mystically connected to some class of magical cadre. As you will have further divined, she is then dispatched to a fusty academy to learn various things from a distinguished English or Irish actor. Lest the connections be lost on their audience, the makers of The Mortal Instruments have – with breathtaking chutzpah – cast one Jared Harris as the hilariously named Hodge Starkweather. You may recall that Mr Harris's father, Richard Harris, played a certain magical pedagogue in an earlier, less frantic fantasy sequence.

The film is based on the first in a series of successful books by one Cassandra Clare. As in far too many recent such adaptations, the film-makers demonstrate their terror of their core demographic by seeking to include every comma, semi-colon and ellipsis from the source material. As a result, we are fire-hosed with a constant, unstoppable stream of information about vampires, werewolves, warlocks and the "shadowhunters" who variously hunt those entities down or form alliances with them. (In one pricelessly silly turn, it is revealed that JS Bach is a shadowhunter.) No concessions are made to those not already familiar with the story.

A spirited Lily Collins tries her best as the busy heroine. Jonathan Rhys Meyers cackles with some enthusiasm as Henry VIII from Hell. There is some surprisingly nasty horror. But the picture never manages to escape from the sheer jumble of its own competing mythologies. If fans of the books want part two, they'd better pay to see this more than once. Nobody else is going to be much interested.