By Nick Romano
August 10, 2017 at 10:15 AM EDT
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In a landmark moment, Prince William, Duke of Cambridge, and his brother, Prince Harry, have sat down for on-camera interviews to discuss the aftermath of the death of their mother, Diana, Princess of Wales. The conversations will air as part of a two-hour documentary, Diana, 7 Days, which will premiere on NBC Friday, Sept. 1 at 8 p.m. ET/PT, the network announced on Thursday.

“Part of the reason why Harry and I want to do this is because we feel we owe it to her,” Prince William says in the doc. “I think an element of it is feeling like we let her down when we were younger. We couldn’t protect her. We feel we at least owe her 20 years on to stand up for her name and remind everybody of the character and person that she was. Do our duties as sons in protecting her.”

Directed by documentarian Henry Singer (9/11: The Falling Man), Diana, 7 Days examines the week between Diana’s death and her funeral. Family members, close friends, political figures, and journalists will be featured, including Tony Blair, Alastair Campbell, Earl Spencer, and Lady Sarah McCorquodale.

Princess Diana died on Aug. 31, 1997 from injuries sustained in a car crash in France, a loss that rippled throughout the world. HBO recently debuted a documentary, Diana, Our Mother: Her Life and Legacy, which focuses on her presence as a mother and was created with the blessing of her sons.

According to a press release for Diana, 7 Days, Prince William and Prince Harry will share their first reactions to the news of their mother’s death, memories of the public mourning period, their reactions on the day of the funeral, personal memories of their mother, and what she meant to them both then and now.

“When she died there was such an outpour of emotion and love which was quite shocking,” Prince Harry says in the documentary. “It was beautiful at the same time, and it was amazing now looking back at it. It was amazing that our mother had such a huge effect on so many people. When you’re that young and something like that happens to you, I think it’s lodged in here, there, wherever — in your heart, in your head, and it stays there for a very, very long time. I think it’s never going to be easy for the two of us to talk about our mother, but 20 years on seems like a good time to remind people of the difference that she made, not just to the Royal Family but also to the world.”

Diana, 7 Days is executive-produced by Alison Kirkham and Peter Dale for the BBC, and produced by Singer, Jenny Saunders, and Jessica Ludgrove.