Picnic at Hanging Rock (1998)

In the early 1900s, Miranda (Anne Lambert) attends a girls boarding school in Australia. One Valentine's Day, the school's typically strict headmistress (Rachel Roberts) treats the girls to a picnic field trip to an unusual but scenic volcanic formation called Hanging Rock. Despite rules against it, Miranda and several other girls venture off. It's not until the end of the day that the faculty realizes the girls and one of the teachers (Vivean Gray) have disappeared mysteriously.