Jacques St. Ives is a high ranking officer in Napoleon's army. He requests a demotion to avoid having to duel officers at his own level. The commander is furious at this request and demotes St. Ives to the rank of private and sends him to the war front.

St. Ives is taken prisoner and is sent to Scotland where the warden, Major Chevening, is a bored British officer who lusts after the lovely local woman Flora. Flora, however, has eyes only for St. Ives. Flora helps Jacques escape.

The remainder of the tale tells of St. Ives adventures as he tries to make his way home. He learns he is accused of murder and has to use his wit to avoid being caught.

Robert Louis Stevenson didn't live to finish "St. Ives". The last six chapters were provided by author Arthur Quiller-Couch.