 By using a mystery bookstore for her background, Hart has given her characters the opportunity to talk freely about other mystery authors and books.One of the ongoing themes of the series is a contest whereby the first customer who correctly identifies a series of five mysteries from the clues in a painting hanging in the shop wins his or her choice of a novel.Hart's Henrie O mysteries feature 70-something retired newswoman, Henrie O'Dwyer Collins, as she travels the country and the world, solving crimes that seem to follow her as she travels.