Bangkok - A Thai-born director who took just weeks to shoot the first film about the dramatic cave rescue of the "Wild Boars" football team says his focus is on authenticity and the mission's "unsung" heroes, with book publishers and Hollywood studios jostling to make their versions of the saga.
Tom Waller says The Cave, which is aiming for Thai release for the July anniversary of the operation, will be a "genuine" retelling of the gripping mission to extract the 12 boys and their coach from the waterlogged Tham Luang cave.
Its cast features more than a dozen of the real-life rescue heroes as well as extras such as the cooks who provided food round-the-clock food as officials and the world's media massed at the cave entrance.
The "Wild Boars" spent more than a fortnight trapped in the dark before divers rescued them in a mission of unprecedented complexity - diving the boys out through twisting passageways while they were heavily sedated.
Waller, a Thai citizen with an Irish father and whose work includes The Last Executioner, said he did not immediately think he would take on the project despite its real-life dramatic arc.
"I thought it was going to be just a magnet for vultures who wanted to cash-in," he said at the office for De Warrenne Pictures in Bangkok.
But then he started dwelling on all the people involved in the extraction, the volunteer spirit of the rescue, and the "unsung heroes that weren't in the newspapers".
"So for me it was almost a question of either make the film now or shut up and wait until Hollywood's made the film and enjoy it like everyone else."
Waller hopes his Thai background may also give him an edge over bigger name foreign directors, while the swift turnaround meant memories are still fresh in the minds of those who took part in both the rescue and the movie.
But challenges remained during the shoot.
The real Tham Luang cave, in northern Chiang Rai province, is off limits, so locations recreating the waterlogged, claustrophobic conditions had to be scouted across the country.
The Cave also broadbrushes over some of the scandalous strands of the drama, which have led to lawsuits and angry social media squabbles.
"People keep asking, who is playing Elon Musk?" Waller said, referring to the Tesla CEO's attempt to provide a submarine and his legal battles with a rescuer whom he insulted on Twitter.
The trailer will be launched at the Berlin Film Festival next month, getting out ahead of bigger, better-funded projects believed to be in the works that may have a wider reach outside of Thailand.
The cave saga has been hungrily-eyed as a money-spinner, with foreign-scripted books and films lining up to gain official approval from the ministry of culture to shoot or interview the boys at the heart of the drama.
Seven months since the rescue at least six books about the rescue are listed on Amazon while speculation is rife that Crazy Rich Asians director Jon M. Chu may enter the fray.
But while large Hollywood studios may stack the cast with A-listers and tinker with the plot for dramatic purposes, Waller's film prides itself on its tethering to reality.
"Everything in the movie is 100 per cent true," said Jim Warny, 36, a Belgian who lives in Ireland and belongs to the niche world of cave divers who were called on to help, and who starred as himself in The Cave.
An electrician by training, Warny said that the period after the rescue was intense, with rescuers inundated with offers, including a request to take reality TV presenters cave diving.
Waller built a different level of trust with him and the verite vision appealed to him.
"A lot of people just wanted to buy life rights or exclusivity, and waving a contract at you and not really focusing on the story before giving you a big lump of cash," said Warny.
"That was something Tom didn't do."