The House of a Thousand Candles oleh Meredith Nicholson

A novel of romance and adventure, of love and valor, of mystery and hidden treasure. The hero is required to spend a whole year in the isolated house, which according to his grandfather's will shall then become his. If the terms of the will be violated the house goes to a young woman whom the will, furthermore, forbids him to marry. Nobody can guess the secret, and the whole plot moves along with an exciting zip.