Lincoln's Sword is alternate history in which the objective events are the same as in our experienced world; the "alternate" aspect is the magical underpinnings that let those with the Sight see alternate futures and try to bring about the least bad. The sword of the title is mostly symbolic; that is, it is an actual sword, but it doesn't kill or maim anyone. It has strange properties, bearing at times brownish stains that can be scoured away but then reappear, or will suddenly show fresh blood, and it tends to bring bad luck to those who possess it, and often an early death, but not through its direct agency as a sword. The main thrust of the story is to choose one's path carefully, on the basis of the likely results of one's actions.

In the Doyle-Macdonald version, Mary Todd Lincoln is a powerful sibyl, who has true visions of alternate futures but cannot affect the course of history. She is helped, however, by two people who can travel through time and act on the knowledge she has given them: her best friend, Mercy Levering Conkling, and a mysterious "Mr. Thomas."

There are many scenes of people going about their normal activities, mostly soldiering on both sides in the Civil War, but presented in Doyle and Macdonald's sure voices as real people living real lives. This is not your usual alternate history, but if you like your real world history spiced up with a touch of fantasy, this is probably the book for you.