The deaths of such an iconic mother-daughter pair, Debbie Reynolds and Carrie Fisher, have left the world reeling from shock.

In a strange twist of fate, the complex (but enduringly loving) relationship between the two is the subject of an upcoming HBO documentary set for release next year, Bright Lights: Starring Debbie Reynolds and Carrie Fisher.

"It’s a love story," HBO Documentary Films president Sheila Nevins told Variety. "Carrie wanted to make Bright Lights for Debbie and Debbie wanted to make it for Carrie. The sudden loss of two women only magnify the importance of Fisher and Bloom capturing the material for the movie when they did."

"If this was a Hollywood script, no one would believe it. They just loved each other so much. The bond was just unbreakable," she tearfully added.

Fisher admitted in an interview with Playlist that her reasoning behind Bright Lights was to preserve the legacy of her mother, this Golden Age Hollywood star best known for the iconic Singin' in the Rain: "It was my idea. My mother was retiring and she’s never really been seen as she is. She’s very candid on stage, but it’s still a performance. I wanted her to compete with me and I thought we were sort of a funny couple."

The film was produced by Fisher Stevens, behind the Leonardo DiCaprio-produced climate change documentary Before the Flood, and Alexis Bloom, who produced Alex Gibney's We Steal Secrets: The Story of Wikileaks.

First screened at Cannes, while also featuring as part of the New York Film Festival line-up, Bright Lights received plenty of critical adulation for its tender and heartfelt tribute to the stars.