Well educated, sensible, and apt to take people in hand, Miss Flora Poste is nevertheless a teenaged orphan without much in the way of finances (at least by her standards). So she resolves to live with relatives, both as a cost-savings and to provide her with material for the novel she intends to write when she is 50. She chooses her second cousin Judith's farm on the basis of the town (named Howling, Sussex), the farm (named Cold Comfort) and Judith's vague mention of owing Flora based on a wrong done years ago. It turns out that Cold Comfort Farm really is as gothic, trite and squalid as she'd imagined, but Flora is not daunted--she sets out to solve the farm's problems one by one, from her arty teen cousin who is sure to be unlucky in love to the farm's nominal leader Amos, who only wants to preach hellfire and damnation.
It is laugh out loud hilarious, with a wonderfully impish tone that never gets annoyingly arch.
(I saw the 1995 movie before I ever read the book, and was astounded to find that nearly all of the dialog and action is word-for-word pulled from the book. Some side characters are combined or removed altogether, but it really is an astonishingly faithful adaptation.)