Picnic at Hanging Rock , 1975. Directed by Peter Weir, and starring Rachel Roberts, Dominic Guard, Helen Morse, Vivean Gray and Jacki Weaver.
https://encrypted-tbn2.gstatic.com/i...9uZwfuJ95w0ICK
Weir recalled that when the film was first screened in the United States, American audiences were disturbed by the fact that the mystery remained unsolved. According to Weir, "One distributor threw his coffee cup at the screen at the end of it, because he'd wasted two hours of his life—a mystery without a goddamn solution!"
Critic Vincent Canby noted this reaction among audiences in a 1979 review of the film, in which he discussed the film's elements of artistic "Australian horror romance", albeit one without the cliches of a conventional horror film.
Despite this, the film was a critical success, with American film critic Roger Ebert calling it "a film of haunting mystery and buried sexual hysteria" and remarked that it "employs two of the hallmarks of modern Australian films: beautiful cinematography and stories about the chasm between settlers from Europe and the mysteries of their ancient new home."
Courtesy of BFI for this film.
A marvellous bit of film making tbh, all the more so because you dont get the closure you strived for:)