Wedding guests arrive on Nantucket for the lavish rehearsal dinner at the Winbury estate, but the nuptials take a tragic turn when a body is discovered.

While police search Summerland for clues, Greer's swift attempt to control the narrative makes Amelia uneasy. A wedding guest tries to leave the island.

Tough questions from Detective Henry deepen Amelia's suspicions. Greer receives a mysterious call. Tensions rise and tempers flare among the Winburys.

As Tag's movements at the party come under scrutiny, Amelia asks some questions of her own. Greer's efforts to throw the perfect book launch go awry.

A twist in the police investigation plunges the Winbury family further into crisis. As long-buried secrets emerge, so does the truth about what happened.