The school has been run since its inception ten years earlier by two elderly educators, Mabel Edge and Hermione Baker, who are regarded by many as old spinsters hopelessly out of touch with reality, especially with what their teenage charges really think and feel.

The 300 or so students are virtually indistinguishable from one another, a fact which is stressed by their names all starting with the letter M: Margot, Marion, Mary, Melissa, Merode, Midget, Mirabel, Moira.

Birt, however, a short and stout man in his late twenties, is having an affair with Elizabeth Rock, a 35-year-old woman recovering from a nervous breakdown who temporarily also lives on the school grounds, in her grandfather's cottage.

The ageing Rock, who is referred to as "the sage" by some (including the narrator) and as "Gapa" by his granddaughter, spends his time mainly with, and for, his pets—his albino sow, Daisy, his cat, Alice, and his goose, Ted.

Edge, one of the principals, has for some time wanted to thoroughly "spring-clean" the whole place and get rid of Rock, his granddaughter, and Birt, partly to secure the sage's cottage for the use of additional school staff.

When in the morning some girls report Mary and Merode missing, pointing out that neither of their beds has been slept in, Edge turns out to be very reluctant to use the official channels to inform relatives, the school supervisor, or the local police.

Meanwhile, Mr Rock is accosted by several of the girls who first want to dance with him and later drag him downstairs into the cellar of the building where they take turns kissing him and where they introduce him to the "Institute Inn", their secret club.