The mysterious death of a great white shark a decade ago is the diving-off point for a captivating marine documentary filmed in the treacherous waters of Bremer Bay in WA.
Back in 2003, wildlife cameraman David Riggs filmed the shark being fitted with an electronic tracking tag. Eighty-seven days later the tag washed up on a beach and revealed the shark had been ferociously eaten alive.
Riggs became obsessed with finding out what sort of sea creature could have taken out the 3m-long great white.
His search for answers led to the discovery of a mysterious natural phenomenon that for a few short weeks each year attracts the ocean's most fearsome predators. He got to the point in his research where he approached the ABC to make a documentary.
Enter Perth filmmaker Leighton De Barros, who has been nominated for four Emmy Awards for cinematography and has marine documentaries such as Whale Patrol, Ocean Giants and The Dolphins of Shark Bay under his belt.
He has worked on 13 series of Survivor, an experience he describes as "an eye-opener", and recently directed and photographed On a Wing and a Prayer for the ABC, about the life cycle of the endangered Caranaby's black cockatoo.
"I grew up in the northern beaches and get a buzz being on the ocean," he says.
"This story contains remarkable coincidence and a bit of science. Dave Riggs is a genuine guy who has stumbled on an amazing ecosystem and the ultimate push for him is to make sure it is conserved.
"He's worked really hard to raise awareness that there's a remarkable environment 50km offshore, out of sight and out of mind, that needs to be protected with regards to exploration.
"It shows if you are interested in your environment, even without being a scientist you can still make your own observations and findings that can be remarkably accurate."
For laymen, the doco's "whodunit" approach to the killing of the shark is an effective entree into the mysterious world of the deep sea.
As the Hercule Poirot of the high seas, Riggs' prime suspects are a killer whale, a giant squid or another great white shark. But there are hints that something even more extraordinary could be lurking in those murky depths.
Two former sperm-whale hunters speak about occasions when their sonar detected a massive creature just below the surface.
"They saw an apparition on their radar, a large mass come below the surface and disappear, and it happened time and time again," De Barros says.
"The whole whaling industry is fascinating. They must have seen some phenomenal things out there and you just have to take their word for it."
For De Barros, the highlight of an often-difficult shoot was being surrounded by killer whales.
"You take a chance trying to film marine animals but we saw them every day, sometimes they would come right up to us."
Next up for De Barros is Project Whale Rescue, the production of a video-based game-training simulator for the whale-rescue industry, which will involve travelling to the Kimberley to capture the birth of a humpback whale.
"That's the good thing about WA," he says. "There are still such pristine areas to explore."
The Search for the Ocean's Super Predator screens on Sunday at 7.30pm on ABC1.