Vampires, werewolves, witches and warlocks. Straight love, gay love and unrequited love. Hidden buildings, hidden people and hidden objects. There’s a lot going on in The Mortal Instruments: City Of Bones… and I can’t help but feel this film has been made for fans of Cassandra Clare’s novel. With a strong understanding of the backstory and the characters, they can simply sit back and enjoy this translation to the big screen.

For everyone else… well, it may be a struggle. There are some interesting ideas and concepts within this fantasy world but they don’t come through clearly enough, despite the 130 minute duration. I had similar thoughts about Beautiful Creatures – another film trying to kick start a new franchise and tap into the Twilight demographic (i.e. younger females).

To put it simply, largely because I can’t quite get my head around the detail, The Mortal Instruments: City Of Bones centres on a teenage girl named Clary (Collins). She can see what others can’t – another world that goes on around us. It’s filled with nasty creatures but the good guys, known as shadowhunters, are keeping them under control.

However, the balance of power is shifting. For centuries, the shadowhunters have controlled a special cup that can be used to transform ordinary people into their kind. It is crucial in ensuring they have sufficient numbers to defeat their adversaries. The cup is now missing. Clary’s mother is the only person who knows it’s location but she has been kidnapped by Valentine (Rhys Meyers), a rogue shadowhunter who wants to use the cup for his own sinister purposes.

The film’s most frustrating element is the number of subplots that aren’t sufficiently resolved. There’s a rushed, too-much-going on-at-once action finale that leaves too many loose ends. For example, one character is bitten by a vampire and we’re shown the two bite marks on his arm. Does anything come of it? Strangely not. I can only assume that all will be revealed in the inevitable sequel.

Those looking for romance might be entertained by the intriguing love quadrangle. Clary falls in love with a young, self-serving shadowhunter named Jace (Campbell Bower). This irks Simon (Sheehan), Clary’s best friend who has had a crush on her for years but has never fessed up, and Alec (Zegers), a gay shadowhunter who has a soft spot for Jace. Again, this is a subplot with potential but it’s not explored deeply enough. It’s a shame we see so little of Alec. He’s an interesting character so why not use him?

I’d happily watch future films in this series. There’s potential. I’d just ask that next time around, we get a little more background and a few more answers.