Picture the scene: It's a wild and snowy night. A man stands on a bridge, staring into the icy river and contemplating his life. We have already been witness to extortion, fraud and domestic abuse. Over the next hour, this man's little brother will drown, and our character will plunge into depression, assault a police officer and crash his car while drunk.
If you're thinking that this is all from a newly unearthed screenplay by Arthur Miller, or perhaps a synopsis of Ken Loach's latest work, you couldn't be more wrong.
Everything above, and more, takes place in It's a Wonderful Life, the "feel-good family favourite" and regular winner of polls to find the public's favourite Christmas film.
The fact that It's a Wonderful Life is a tad downbeat is nothing new. For decades, the film has attracted as many humbugs as it has admirers, by virtue of it being "too depressing". Love it or hate though, there is no denying that by the end of Frank Capra's film that elusive warm fuzzy feeling is well and truly kindled.
However, if a good Christmas movie can be judged by how Christmassy it makes you feel (Christmassy being a complex scientific measurement best described to the layman as "happy, hopeful and harmonious with a slight tinge of sadness"), then modern festive films fail on almost every count, and I know why.
Simply put, they're just not miserable enough. By playing it safe and desperately trying to not upset or offend anyone, Christmas films today miss the key element required for success: despair and salvation – the light at the end of the tunnel.
Not just any old salvation will do either, it needs to be relief from a predicament verging on the catastrophic. The dilemma of accidentally agreeing to attend too many Christmas gatherings (as seen in the stupendously bad Four Christmases) isn't the sort of thing that will ensure your film is broadcast year after year, it's just a bad copy of a Vicar of Dibley episode.
Modern "holiday" films fail to ignite Christmas spirits because they're too concerned with crowbarring in cheap laughs, outfit-change montages and someone unlikely (elf, old person, Vince Vaughn) doing a hilarious "urban" dance.
This isn't to say that more recent festive films are routinely unenjoyable nonsense, far from it. Aardman Animations' Arthur Christmas is one of the best films released this year of any genre.
However, while it is a sparkly bauble capable of entertaining multiple generations, will it be fondly regarded in 15 years? As a fun film – yes. As a Christmas classic – no. While it has the usual story arc which sees characters down on their luck and down in the dumps at the start of the final act, there is no genuine pathos, no dolor, nothing that would cause the pixellated, bulbous-nosed characters to fall to their knees, rail against an unjust universe and wish that their animators hadn't bothered rendering them in the first place.
Take a look at some of the other all-time favourite family Christmas films, and you'll see that – far from erring on the side of caution in a vain attempt to rake in as many box-office dollars as possible – they take risks, throw their characters into turmoil, and are all the more successful for it.
On the surface, Home Alone is a knockabout children's comedy. Dig a little deeper though, and you'll discover that as well as being funny, moving and scary in the right places, Home Alone works because it doesn't shy away from danger and unhappiness. Strip away the slapstick, and we're left with two burglars intent on burgling a house containing an eight-year-old who has been abandoned by his parents.
Meanwhile, the eventual hero of the story is a depressed, isolated old man, shunned by his community because of rumours he killed his family. Ho-ho-ho.
What about the perennial favourite, Miracle on 34th Street? The first half of the film is a commentary on the rampant commercialism that has permeated what is supposed to be a religious holiday, while in the second half we are treated to the sight of a kindly old man wretched and alone in a psychiatric hospital because his genuine good nature is viewed as dangerous and a sign of mental illness. It's a jarring moment and stirs up a maelstrom of thoughts about our own elderly relatives who may be left languishing in a home while the rest of us are celebrating, but it is this glimpse of harsh reality that makes the ending so magical.
When the denouement comes and the judge overseeing the case to keep the old man in a home is forced to accept that, yes, this kindly gent is indeed Santa Claus, it is all the more gratifying.
Salvation is sweetest when you have been in the depths of despair, and film-makers today overlook this universal truth. Instead, we are given cheesy flicks with hastily thrown-together scripts, starring actors who spend the whole shoot thinking about the new houses they are going to buy when the cheque clears.
Even now, just thinking about The Holiday, a trite, saccharine, vacuous lump of yuletide tat starring Jude Law, Cameron Diaz and Kate Winslet makes me gag with rage.
Only slightly better are the slew of unconventional Christmas films (Bad Santa, Rare Exports, and this year's A Very Harold and Kumar 3D Christmas) that greet us each winter. But it's easy to subvert a genre with gore and bad language, far harder to create something that appeals to families.
However, those films trying to appeal to a wider audience could do well to borrow from the unconventionals, for it is a certain darkness that gives successful films their absolutely essential sparkle.
It's antithetical, but loss, unhappiness and hardship are what produce a feel-good film. It's no surprise that A Christmas Carol remains so popular and is so regularly adapted.
A proper Christmas film needs to have a dark heart buried within, one that pumps out bleak visions of the future populated by sinister characters.