Business is booming at the Lazy Mermaid Lobster Shack and Aunt Gully is thinking about branching out. When Ali and Lorel start catering private parties to bring in enough money to buy a food truck, they enter the elite world of Long Point, the wealthy enclave connected to Mystic Bay by a stone causeway. Things get awkward when Ali realizes that Katherine Slocum, the Long Point hostess with the mostess, is dating her sister Lorel's old flame, Patrick Yardley. When Katherine is found dead on her yacht, Empress of the Seas, after a Fourth of July party, Lorel falls under suspicion, and Ali realizes that family secrets are the deadliest secrets of all.