The eighth detective

All stories about the murders are subject to the rules - at least, there is a victim, a detective and a suspect.
Thirty years ago, the professor of mathematics Grant Macalliste figured out these rules and wrote seven beautiful detective stories. But it was too long, because now Grant lives a hermit on the Mediterranean island, calculating the rest of his days.
Suddenly, like a devil from a snuffbox, Julia Hart appears in the life of a grant, an ambitious editor who passionately wants to reprint those very detective stories. Now the writer, who is hiding from his past, and the editor, striving to understand, must work hand in hand. But only in the stories of the grant is full of inconsistencies - or, perhaps, tips that will lead to a new, eighth secret?