I don’t know when I first heard the axiom, “the devil is in the details,” but it is certainly true when it comes to writing mysteries. Mathematically, the ages of characters and dates of events must be worked out in advance. Many a time I have written a paragraph mentioning the age of a character only to realize her parents would have to have been in their sixties when she was born. I am not dealing in fantasy. When writing a series with multiple generations, I must do a great deal of addition and subtraction to make everything work before I begin typing.

My Sweet Iron series necessitates mathematics. The plan for this series is to have Beth Russell investigate past generations in various times in history so she can find out about her own biological family. I smile because now I have a good reason to research some of my favorite historical ages. But first the numbers must be run so that everything fits together in the details.

I began with A Death at Tippitt Pond and worked out the mathematics of the present generation. Starting with Beth Russell’s family, her parents were born in 1919 and 1929. Beth was born in 1969, so her mother would have had her at age 40. This works with the premise that her parents wanted to have children, and Beth was a late child. That’s what they told her. However, as we find out, Beth was not the biological child of the Russells. This means another set of dates. Her biological mother was born in 1952, making her 17 when she had Beth, and her biological father was born in 1950, so he was 19. Keeping this all straight necessitates a timeline. Most writers use timelines because the devil is in the details.

The second and third books in the series, yet in the writing stages, involve Beth’s research into her ancestors. Now the timelines become even more important, so multiple generations make sense date-wise and age-wise. Each book will have a plot in the present and a plot in the past.

If the first settlers came to Sweet Iron in the 1830s, W.W. Tippitt, who built Tippitt House, came in the second wave in 1840 when he was 31. His daughter, Abigail, was born in 1834 before W.W. came to Sweet Iron. By 1865, at the end of the Civil War, Abigail is 31 and marries, having a daughter, Emma, in 1866. W.W. by then is 57 years old and a grandpa. This is the family and time period that Beth will research in the second book.

The third book in the Sweet Iron series will be set in the Gilded Age, my favorite. Emma has a child in 1891, Josephine, when Emma is married and 25, and her grandfather, W.W. is 82. Since the 19th Amendment passed in 1920, this child, Josephine, will be a suffragette at age 28.

My brain hurts from all this math.

The devil is in the details when it comes to plotting out generations in a series of books. Now that I know the ages and dates of the second and third book, I am on a clear writing course. No one told me when I became a writer that I’d have to also conquer math.