Grace Livingston Hill 
Crimson Mountain 

Beautiful Laurel Sheridan, once wealthy and sheltered, is now orphaned and nearly destitute. Undaunted, Laurel gets a job teaching in the little town of Carrollton, near beautiful Crimson Mountain.
Then she encounters handsome Phil Pilgrim, who is home from the army to sell his family homestead to the government for a munitions plant. Thrown together by a freak accident in which Phil saves Laurel’s life, the two discover a deep friendship that quickly blooms into much more. And though Phil must return to his army duties, Laurel is secure in the knowledge of his love.
Then one night she overhears a group of men plotting to blow up the new munitions plant! Unsure who she can trust in the small town, Laurel desperately tries to contact Phil, seeking his aid and counsel. But will he be able to save her from the web of deceit and danger that is slowly closing around her, threatening her life and her country?