Spoiler culture is at least in part responsible for The Avengers' success. Photo / Supplied
With major franchises like Game of Thrones and Marvel's current MCU coming to an end this year, spoiler culture has never been bigger.
Studios and stars alike have been urging fans to keep plot points secret so other viewers get the maximum impact, but this is nothing new. Fearof spoilers is good for business - it always has been. Here's why:
On May 1 1999, bookshops around the world began selling an item that today would be considered commercial hara-kiri.
It was the complete illustrated screenplay of Star Wars: Episode I - The Phantom Menace, written by George Lucas and accompanied by hand-drawn storyboard panels showing scenes from the forthcoming film.
That's right: forthcoming. Because The Phantom Menace itself would not be released in cinemas for another two and a half weeks, by which point any interested party could have familiarised themselves with the entire plot of one of the most hotly anticipated films ever made.
The Phantom Menace became the fastest film to reach the $100, $200 and $300 million box-office milestones. Yet today, studios guard the plots of blockbusters like state secrets, and for the most part - a small community of indefatigable snoopers on websites such as Reddit notwithstanding - cinemagoers wouldn't have it any other way.
That's because the industry has become obsessed with spoilers: a word that originally referred to unwanted foreknowledge of plot twists when it came into use in early online discussion groups, but that has recently come to refer to an advance awareness of any aspect of a film or television programme that hasn't been revealed in its marketing push.
For the recently released Avengers: Endgame, spoilers encompassed everything from the fates of Iron Man, Captain America and Thor to incidental character punchlines, such as the Incredible Hulk's newfound fondness for cashmere jumpers. Such was the secrecy surrounding the project that the members of the cast were handed their dialogue on a day-by-day basis and none ever saw a complete script.
On set, spoiler culture has created the plot equivalent of green screen: just say your lines and pretend the story's all around you.
A similar air of mystery blankets Game of Thrones, a television programme that behaves like - and costs about as much as - a blockbuster franchise.
Last Sunday's episode featured the deaths of seven key players, each of which was presented as a twist in its own right. Part of the fun of watching is not knowing when your favourite character is going to be poisoned, beheaded or flung off a cliff - and woe betide anyone who lets it slip before you've had a chance to catch up.
Fear of spoilers is good for business: Alfred Hitchcock knew that. It's why in 1960 he emblazoned the posters for Psycho with slogans like "Don't give away the ending, it's the only one we have", and warnings that latecomers would not be admitted, so as to preserve the shock value of Janet Leigh's early departure.
But he believed the unspoilt viewing had a genuine artistic value too, and bought up all copies of Robert Bloch's source novel when it was published in 1959 in order to keep its twists under wraps.
Today, studios cultivate spoilerphobia at the behest of directors, but also because it makes commercial sense. It corrals critics into an outgroup marked "not necessarily to be trusted", and allows pre-release teases to be packaged as news. Most importantly, it sends opening-weekend numbers stratospheric, as audiences scramble to enjoy the authentic, tabula rasa experience.
Avengers: Endgame made $1.2 billion on its opening weekend; Game of Thrones' most recent episode drew 17.4 million viewers on its day of broadcast in the US and a further 3.4 million in the UK, including 192,000 who watched it "live" at 2am.
Yet the lesson - intended or otherwise - is that films and television shows don't mean anything beyond what happens in them: they're effectively just dramatisations of their own Wikipedia summaries.
Roger Ebert, the great critic, died in 2013, before widespread spoilerphobia took hold. He was wary of giving away too much in his reviews, but he also knew that plot was topsoil, and what really mattered about a film was buried deeper than that.
"A movie is not about what it is about," he once wrote. "It is about how it is about it."
Secrets can be fun, but to appreciate art, we need to talk.