Shadowhunters Jamie Campbell Bower and Lily Collins. FILM OF THE WEEK: It's a little bit Twilight. It's a little bit Harry Potter. Heck, it's even a little bit Percy Jackson. It's also a whole lotta hooey. Though hardly the most right-on play at the lucrative young-adult blockbuster market, it would be unwise to write off the first Mortal Instruments movie as a totally derivative dud. Based on a popular series of novels by Cassandra Clare, City Of Bones displays just enough potential - largely by virtue of a welcome, self-mocking sense of humour - to suggest it could be a franchise worth sticking with in the long run. At one point in City Of Bones, its main character, Clary (Lily Collins), declares with some exasperation that "this is so confusing." You just have to give this young woman high marks for honesty, because the restless plotting of this movie never engages with one coherent idea for long. It's like someone accidentally fed the only copy of the screenplay into a paper shredder, then quickly stuck back together what they could and starting filming anyway. Yep, this is one of those movies where a faint gist of what is going on is all you're gonna get. And is all that fervent Mortal Instruments devotees probably need. Clary is a pretty girl in her late teens. A Bella Swan with better social skills, Clary may or may not be a full-blooded Shadowhunter. This issue may or may not be clarified by the end of the movie. A Shadowhunter is a kind of angel that dresses like an extra from a Resident Evil sequel, and struts about exterminating demonic beings of all shapes and sizes. When Clary learns her recently vanished mother (Lena Headey) is a Shadowhunter, her search draws her deep inside a dangerous alternate universe co-existing with ordinary human life in New York City. Clary's guide, guardian and mentor as she totters through this spooky Goth-tropolis is the strapping young Shadowhunter Jace (Jamie Campbell Bower). This snake-hipped smoulder machine may or may not become her boyfriend by the end of the movie. Winning the approval of Jace's disapproving entourage (not unlike Twilight's Cullen clan, but more chatty and less stare-y) can only help Clary in this regard. The ever-insistent presence of Simon (Robert Sheehan), Clary's bespectacled best-friend-with-a-crush, sets up a lightweight love triangle that fans of this stuff traditionally expect. For those not sure if they really want to play along with the Mortal Instruments effect, making it through the 130-minute running time could be an ordeal. The only option for the unconvinced is to focus on the nuttier stuff sprinkled across this tale. It is clever enough to warrant a knowing chuckle at the very least. Did you know demons have an abiding fear of certain musical notes? Or that the great composer Bach was a Shadowhunter? Neither did I. Oh, and you know how Twilight reckons all werewolves are hunky young dudes in denim shorts living deep in the woods? City Of Bones is here to tell you that's a lie. The Mortal Instruments' werewolves are burly, bearded bike-ridin' guys well into their forties. So there. Director: Harold Zwart (The Karate Kid) Starring: Lily Collins, Jamie Campbell Bowers, Lena Headey, Robert Sheehan, Jonathan Rhys Meyers. Often out of tune, sometimes dead catchy Rating: 2.5/5