Premiering June 10th at New York City’s Tribeca Film Festival is The Lost Weekend: A Love Story. The doc chronicles John Lennon‘s 18-month affair with assistant May Pang during his and wife Yoko Ono‘s separation during the period dubbed, “The Lost Weekend.”

The film, which was directed by Eve Brandstein, Richard Kaufman, and Stuart Samuels, features interviews with photographer Bob Gruen, Apple Records manager Tony King, solo-Beatles drummer of choice Jim Keltner, along with John Lennon’s older son, Julian Lennon.

Pang, who prior to her affair with John Lennon, served as his and Yoko Ono’s personal assistant, and was responsible for coordinating the production of such Lennon albums as Mind Games, Walls And Bridges, and Rock ‘N’ Roll, along with Harry Nilsson‘s Lennon-produced album Pussycats. Although her relationship with Lennon ended publicly in 1975, according to Pang, the couple remained periodic lovers through 1978.

She’s published two books focusing on her time with Lennon — the salacious 1983 memoir, Loving John, and the 2010 photo book, Instamatic Karma.

Even today, May Pang is amazed that people are still clueless about the extent of her and Lennon’s relationship: “I had a relationship. People weren’t ready that there was something like that, which actually did happen. People didn’t realize how long it was. I’ve seen people say in fanzines or Q&A’s — ‘Why is May Pang writing this book, she only spent a weekend with him?’ Which is funny — it was almost two years.”

May Pang revealed in her book Loving John that long after the “Lost Weekend,” the Little River Band‘s “Reminiscing” actually became her and Lennon’s “song”: “The song that he liked, and he would think about me by the Little River Band. In ’78, he came up and he said, ‘I just heard this song on the radio.’ And I said, ‘What song?’ And he started to hum it to me. I said, ‘I can’t believe that you’re asking me about this song.’ I said, because another musician friend of mine just said ‘Oh! This song! ‘Reminiscing’ It’s such a great song.’ And here John is saying the exact same thing. And I happened to have the record, and he goes, ‘That’s it!’ And he made me play it over, and over, and over.”