Inside the Lines

Inside the Lines is a romance-tinged spy thriller written by Earl Derr Biggers, first published in 1914. Set against the backdrop of World War I, it follows a young American woman caught in Europe who realizes she may have overstayed her business trip. The story begins on a train from Calais to Paris and culminates in Gibraltar, featuring a mysterious British officer. This novel, based on a 1915 play, was adapted into silent and sound films in 1918 and 1930, respectively, and is notable as Biggers' third novel before he gained fame for his Charlie Chan series.