Pearl is 10 and her older sister, Jodie, at 14, is beginning to run wild. In an attempt to stop the rot and make a new life for the family, their parents take new jobs at Melchester College, a posh boarding school miles from anywhere. Their mum is to be school cook and their dad the caretaker. They arrive at the beginning of the summer holidays and bookish Pearl is entranced by the splendid if crumbling Gothic mansion. Even Jodie, surprisingly, seems to relish their new surroundings, hitting it off with the eccentric headmaster and setting her cap at handsome gardener, Jed. Pearl, too, finds a new friend in the shape of gangly intellectual Harley, and soon they're badger-watching in the extensive grounds of the college.

But when term begins, Jodie's problems resurface as she finds herself ostracised by her classmates. Increasingly, she is at odds with her family and everyone else, retreating instead to the solitude of the out-of-bounds tower room. Pearl has always adored her sister, despite their deep differences in personality, and tries desperately to maintain their special relationship but tragedy looms as events begin to spiral out of control...