My novel is based on the true, strange, and heart-breaking story of, as the title says, “The Last Prince of the Mexican Empire.” If you’ve never heard of Mexico’s little half-American prince, not to worry: even many beautifully educated Mexicans have not.

Mexico’s 19th-century history is, to make an understatement, labyrinthically labyrinthical. (I like to say, if you’ve heard of Santa Anna and you know that Cinco de Mayo is not Mexico’s Independence Day, you’re doing OK.) Many Mexicans would prefer not to dwell on the Second Empire of Maximilian, a period also known as the French Intervention. Royalty, foreign invasion: not an appetizing combination for many.

Furthermore, when I came upon the story of Mexico’s last prince, and began to read more deeply, I soon realized that the little that had been published about him was riddled with errors and a mystifying vagueness. And so began my plunge into nearly a decade of research in archives from Mexico to Vienna to Texas and Washington, D.C.

The Last Prince of the Mexican Empire came out in hardcover last year; this May 5th marks the publication of the paperback edition (and yes, a Spanish version comes out this fall). One of the most surprising and delightful things about traveling around the U.S. and Mexico promoting it has been hearing the stories other people tell me about their connections to this time.

“A procession of the damned. By the damned, I mean the excluded… We shall have a procession of data that science has excluded.”

I was 11 years old when I read those words for the first time. They were the opening lines of The Book of the Damned, quoted by Daniel Cohen. I was already a regular visitor to the 130 section of my public library. But that was when I first learned about Charles Hoy Fort.

No joke: he changed my life. And he continues to change it. Blood Oath, my first novel, is going to be published on May 18. It’s about a vampire who works for the President of the United States. It’s a combination of the spy thriller and the horror story, and includes many of the anomalous chunks that don’t fit in the regular American history books.

It wouldn’t exist without Fort.