“A Perfect Couple”, this season’s beach read by Elin Hilderbrand, opens on a somber note. The maid of honor for a society wedding is found floating face down in the harbor on the morning of the big day. Its as if a grey Natucket fog were rolling in–or if Robert B. Parker story was writing a beach read. But this is Hilderbrand, the reigning queen of the summer beach read. So, when the police meet the suspects, they find one comically dysfunctional family. The groom is smitten; the bride wants out. The groom’s mother is a famous mystery whose career is sinking. What follows is a “clever whodunit” mixed into to Hilderbrand’s trademark “light-as-air” confection (Kirkus Reviews).