"The Truth Shall Not Sink with Sewol," a.k.a. "Diving Bell," had stirred strong emotions long before Asia's largest film festival opened last week.
The documentary focuses on botched rescue efforts surrounding the April 16 sinking of the Sewol ferry that claimed more than 300 lives -- most of them high school students.
Blamed by many on regulatory failings, corruption and official incompetence, the disaster plunged the entire nation into mourning and triggered a lasting wave of public anger and disgust.
With emotions still running high six months later, some accused the film of being overly-politicised and insensitive, and the mayor of Busan -- as well as some relatives of the ferry victims -- demanded it be withdrawn from the festival.
In response, dozens of filmmakers urged the festival organisers to stand firm and let the audience make up their own minds.
Co-directed by Ahn Hae-Ryong and prominent leftwing journalist Lee Sang-Ho, the documentary details Lee's reportage from the site of the tragedy and his angry commentary on the rescue operation.
A central figure is a volunteer diver named Lee Jong-In, who argued that he had a special diving bell that could spur the initial rescue effort when there was still some hope of finding survivors.
The movie then describes the highly-public squabble the two Lees had with the authorities in their bid to have the diving bell deployed.
Coastguard and naval officials argued that independent efforts would only hamper the main rescue drive.
For their part, the Lees claimed the authorities stopped them in order to hide unspecified "unknown truths" about the disaster.
The highly-emotional film shows the two men berating state officials as "murderers" and "devils" and criticising the local media for not supporting them.
In the end, the diving bell was briefly deployed but swiftly withdrawn after it proved ineffective.
Director Lee acknowledged the bell's failings but argued that the film would still help shed light on the failures of the overall rescue effort.
"This disaster laid bare the sheer lack of competency of this government ... but people are increasingly forgetting what caused it to begin with," Lee said after the premier.
"I hope that this movie will help unite South Koreans again like they were in the wake of the accident in April," he said.
Some audience members, including the director, wore yellow ribbons on their chests in memory of the victims, and some wept at the footage of the capsized, sinking ferry.
Among the audience was Joshua Oppenheimer, the director of the Oscar-nominated documentary "The Act of Killing" on the mass anti-communist killings in Indonesia in the mid-1960s.
"Thank God they have screened the film," Oppenheimer said. "If they hadn't, this film festival would have gone down in shame and notoriety."
A group of 1,123 South Korean movie directors, actors and other film industry representatives released a joint statement last Friday, calling for the quick launch of an independent investigation into the Sewol disaster.
- Jung Ha-Won