Picnic at Hanging Rock by Joan Lindsay

Picnic at Hanging Rock by Joan Lindsay (1967, approximately 190 pages) is a historical fiction novel set in Australia. It is considered to be one of the greatest Australian novels ever written.

From Goodreads:
"It was a cloudless summer day in the year nineteen hundred.

Everyone at Appleyard College for Young Ladies agreed it was just right for a picnic at Hanging Rock. After lunch, a group of three of the girls climbed into the blaze of the afternoon sun, pressing on through the scrub into the shadows of Hanging Rock. Further, higher, till at last they disappeared.

They never returned."

There are multiple copies available in English and Swedish at the Stockholm public library.