Content Warning: The novel mentions miscarriage and the death of an infant.

On Thursday, August 22, Nantucket’s police chief, Edward “Ed” Kapenash, celebrates his retirement dinner. After a massive heart attack in February, he’s decided to see out one last summer before he finally retires. His last official day is in four days on Monday, August 26.

The retirement dinner is attended by Ed’s wife Andrea, his daughter Kacy and son Eric, Eric’s girlfriend Avalon, and close friends Addison and Phoebe Wheeler, and Jeffrey and Delilah Drake. The Kapenashes, Wheelers, and Drakes call them themselves “the Castaways,’ […] because they all ‘washed ashore’ on Nantucket decades earlier” (5).

Kacy’s friend, Colleen “Coco” Coyle, was invited, but she is working—she is the personal concierge to the Richardsons, a couple who came to the island early in the summer. However, after numerous strange things happened, Ed chose not to invite them to the dinner; the Richardsons are instead throwing a sunset sail party aboard their yacht Hedonism.

Toward the end of dinner, Ed gets a call: The Richardsons’ house has burned down; Coco, who was on the yacht with them, is missing.