My girlfriend owes me a Bank Holiday.

There were so many better things we could have done on a rare lazy Monday off work than see this shitstorm of a film — a lazy pub lunch, lying in ‘til noon, pulling our toenails out with hot pliers, you know the sort of thing. But no. I agreed to go and see Mortal Instruments: City of Bones.

For those not familiar with the book, City of Bones is about Clary Fray (Lily Collins) who, when her mother disappears, discovers she is some kind of warrior angel put here to protect the world from demons. Clary teams up with Jace (Jamie Campbell Bower) and his band of S&M misfits, which breaks the heart of her mortal friend and misfit of another kind Simon (Robert Sheehan). Oh yeah. There’s a magic cup, too.

Following this so far? It’s your typical teen lit fantasy adventure hoping to cash in on some of that post-Twilight box office money.

Clary has a lot to deal with right from the get-go. First she starts uncontrollably drawing strange symbols for no apparent reason, then she starts to see things that nobody else can. Before she has time to start popping antipsychotics she’s whisked off into a fantasy world by Jace to find out what’s happened to her mum.

In between getting her mind probed by monks with no mouth, crashing a warlock’s birthday party, breaking into a vampire hotel and getting a makeover that makes her look like someone from an NSPCC advert about child prostitution she manages to somehow get involved in an incredibly clichéd relationship with Jace, who is pretty much the cockiest little shit imaginable.

Somewhere in the middle it’s pointed out that Alec, one of Jace’s crew of leather-clad demon fighting vigilantes, is also in love with him in the most pointless and emotionless subplots ever constructed. I’ve found things in my bellybutton with more emotion than Alec in the scene where Clary confronts him about this. What could have actually been an interesting, worthy subject — that of unrequited love and the stigma that homosexuality faces in the Shadowhunter culture — is brushed aside because it’s far more interesting to show Jace and Clary making eyes at each other.

Then again, the film isn’t prepared to risk any hint of controversy and depth. Jace and Clary spending a large chunk of the film snogging in a magical garden whilst rain falls upon them and a power-pop ballad plays in the background in a scene that came straight out of the imagination of a 47 year old virgin whose most fulfilling relationship is with her cat, Mr. Muffin. My girlfriend tells me that (spoiler alert, in case you give a shit) in the book, after all this kissing it’s revealed that Jace and Clary are brother and sister. You only find out in book three that this isn’t true, but in the film they clear it up for the audience straight away, whilst leaving the star-crossed teens full of incestuous passion. In a film full of death and violence and blood and betrayal, they’re too scared to take on anything new. It’s pathetic.

To sum up, this film is terrible. In every way, terrible. It’s badly written, painfully acted, woefully directed, full of lazy cinematography and features a soundtrack that sets my teeth on edge. I’d take a guess that even the catering on set was appalling. I swear, the only reason Lena Headey deigned to star in this was that she’d be getting a buttload of money for, like most of the audience, being asleep the whole time.

And what’s worse is when browsing IMDb this morning I noticed a sequel is on the way. Quite frankly, I’d rather talk to the leather-clad man that talks about demons on the bus.