Life being what it is, you sort of know the ending. Sooner or later, you're going to die. Sorry for giving anything away, but you are. One day the screen will turn black, the credits will roll and you'll be left sitting there thinking to yourself: Well, was that it?
Art, however, isn't like life. Or at least you hope it's not. You want to come to the dramatic close and be surprised, not disappointed. You want to be able to enjoy the various plot twists and turns, resulting in a glorious: "Boy, I didn't see that coming" conclusion. Which is why for millions of fans, the leaking of the finale of season 4 of Sherlock was hardly welcome news.
Ultimately though, it wasn't a big deal. Most folk who knew kept quiet. On the other hand, its actual transmission was a very big deal indeed. At the same time as it was going out on TV, it was also being shown at selected cinemas across the country with the added enticement of extra footage. This was an accolade not even afforded to the BBC's last ever Great British Bake Off and in PR terms, it worked. By the time I tried to book, my local arthouse had already sold out.
Whether it was an accidental error or something more sinister and deliberate (let's go for the latter - far more baleful and in keeping with the nature of the programme), we apparently had the Russians to thank for the spoiler.
What with their supposed involvement in the recent US Presidential election and now this, one wonders what else our comrades could soon end up ruining for us? Let's keep a close eye on the Top 40 because if next week's No.1 is a re-release of Back in the U.S.S.R. then questions might need to be asked.
As far as entertainment is concerned, the element of surprise is frequently the most important factor. It's the thing that made the Sixth Sense such a big hit at the box office and the reason Agatha Christie's, the Mousetrap has been running for 65 years.
Of course, there are those of us who like the familiarity of the cultural comfort blanket and wrapping ourselves up in it on a cold January night to watch Godfather II once more.
But for the majority of people, being aware of what happens in a book or knowing how a play, film or television series concludes means there's just no point in reading or watching it.
We've all been behind the person in the cinema queue who loudly says to their companion: "I saw this the other day and right up to the end, even I had no idea the policeman was the murderer".
You can therefore understand why those involved in Sherlock might have wished to keep tight-lipped about their own production.
Unfortunately, my cat like curiosity didn't get the better of me. More's the pity. If only it had, I certainly wouldn't have bothered to sit through such unutterable tripe. This was an episode that literally had everything thrown at it and not in a good way.
At times, it was difficult to tell what you were watching: The Silence of the Lambs, Shutter Island, Sleuth. Those who had accused this mini three parter of being a bit too Bondian would have felt vindicated in their criticism since the family home of Sherlock and Mycroft looked to be a dead ringer for Skyfall, the family home of the young 007.
If the preceding two episodes were trying to be too clever for their own good and failing as a result, this last one was far dumber, with it taking Holmes practically the whole 90 minutes to work out what the viewing public had already fathomed in the first few minutes. Namely that the girl on the plane full of unconscious passengers was none other than Eurus Holmes, the deranged, out of control sister whose only reason for being quite so potty was because she had no one to play with when she was younger. I think we can now add a crazy Latin American day time soap opera to the list of creative references.
I'm not entirely certain if this was a typographical error, but in another review I read, Eurus was written as Euros, which made me think that maybe there genuinely was something subliminally sinister going on with a deliberate attempt to destabilise the single currency. But no. If that were the case, Eurus Holmes would surely have gone by the name of Theresa May.
Should season 5 of this Sherlock TV reboot happen - although it doesn't deserve to, it's almost a given - fingers crossed its creators take a long hard glance back at the original source material.
After all, we wouldn't want the memory of the country's greatest fictional detective spoiled forever.