In the Scottish Highlands, in the glen where MacAllister lives, it has always been the custom to leave a piece of land called the "Goodman's Croft" for the use of the sidhe, the fairy people. But MacAllister has fallen in love with a pretty girl called Peigi-Ann, and decides to plow the Goodman's Croft along with the rest of his land in order to make a good enough living to marry her. He thereby brings on himself the wrath of the proud sidhe, but being a stubborn man, he vows that if he cannot use the land, neither shall they. MacAllister, and later his wife, son and even their faithful hunting dog Colm, must call upon all their wit, courage and humanity if they are to prevail against the various magical attacks of the vengeful sidhe.

Mollie Hunter combines elements of Celtic mythology and children's dreams of heroism in this beautifully written fantasy. McAllistair's vow not to give the fairies their traditional share of his land is followed by several attempts on his life. When at last they kidnap him and make him their slave, his twelve-year-old son Fergus and his aged hunting dog Colm set out to rescue him from the mountain where he is held prisoner under the all-hearing great gray stone giant An Ferla Mor.