Death in the Off-Season by Francine Mathews*

Merry Folger is detective on Nantucket and finds herself trying to prove herself as competent to her chief police father.  She is the detective on the scene when Rusty Mason is found dead in his brother's cranberry bog.  The Mason family is an established, wealthy one and his death causes quite a stir.  Can Merry wade through the family secrets and illegal activity to discover the true murderer? 
I thoroughly enjoyed this light read.  Well developed plot and characters.
Warnings: some swearing, a mistress to a married man is introduced (but nothing sexual is  written about it), one male character remembers his first sexual relation with his old girlfriend (nothing explicit is mentioned)
-Borrowed via Inter-Lib. Loan as my county library system does not own this series.
*Highly recommend for adults.