''The Secret at Lone Tree Cottage'' is the second book in The Dana Girls Mystery Stories series, originally published in 1934 under the famous Stratemeyer Syndicate pseudonym Carolyn Keene. While the pseudonym is most famous for the Nancy Drew series, this specific book follows the amateur detective sisters Jean and Louise Dana as they attend the Starhurst Academy boarding school.
The story begins during the school year when the Dana girls' beloved English teacher, Miss Tisdale, mysteriously disappears. The sisters discover her car abandoned on a nearby road with the keys still in the ignition and clear signs of a struggle.
As they dig deeper, they learn that Miss Tisdale has been secretly supporting her widowed twin sister, Mrs. Brixton, who was disowned by their parents after her marriage. Mrs. Brixton has been receiving threats from her late husband's former business partner, making him the prime suspect in the abduction. Because Miss Tisdale's father is in incredibly frail health—and the shock of the kidnapping could be fatal—the girls cannot go to the police. Instead, Jean and Louise team up with their Uncle Ned Dana to launch a private rescue mission and uncover the dark secrets surrounding Lone Tree Cottage.
