The actor died in 2008 at just 28 of an accidental prescription drug overdose. He won a posthumous best supporting actor Oscar for his role as the Joker in "The Dark Knight," which was released after he died.
The film interviews numerous famous friends of Ledger's. including director Ang Lee and actors Ben Mendelsohn and Naomi Watts. His groundbreaking role in "Brokeback Mountain" is also remembered.
"Heath was the most alive human," says musician Ben Harper of the actor. "If it wasn't on the edge, it didn't interest him."
Ledger, known best to audiences for his work in front of the camera, is often shown in the trailer operating a film or still camera. "He was always a director," says childhood friend Trevor DiCarlo. "Acting was just a way to get there.
The film will also receive a limited theatrical release beginning May 3, Deadline reports.