Celeste is a 28-year-old zoologist and assistant director at the Bronx Zoo. She feels out of place in the wealthy high-society world of her fiancé's family on Nantucket. Grounded and deeply loyal to her parents, she grapples with wedding nerves and her true desires.

Benji is the wealthy, privileged groom-to-be who works in corporate social responsibility at a Manhattan bank. He loves Celeste and relies heavily on the comfortable security of his affluent family. He often remains purposely ignorant of the darker realities beneath their perfect facade.

Merritt is a 29-year-old public relations executive and social media influencer serving as Celeste's maid of honor. Beneath her glamorous outgoing exterior lies a tender heart and deep vulnerability. She navigates alienation from her own family and actively seeks lasting love and security.

Shooter is an independent 28-year-old entrepreneur who runs an expensive retreat company called the A-List. Accustomed to making his own way without family wealth, he serves as the best man but harbors hidden feelings that complicate the wedding weekend.

Greer is the immaculately dressed mother of the groom and a highly successful author of murder mysteries. She is deeply invested in presenting the illusion of a perfect family. She meticulously manages the wedding preparations while battling private anxiety over her husband's behavior.

Tag is the wealthy, charismatic patriarch of the Winbury family. Accustomed to the privileges of his status, he enjoys the finer things in life and expects his family to support him. He frequently acts without regard for the consequences his behavior has on others.

Chief Kapenash is the righteous, objective head of the Nantucket Police Department. Serving as the moral compass of the investigation, he refuses to let the wealth and privilege of the suspects influence his pursuit of the truth.

Karen is Celeste's devoted, middle-class mother who works at a crayon factory gift shop in Pennsylvania. Battling terminal metastatic breast cancer, she views the wedding as a grand finale and wants nothing more than to see her daughter secure and happy.

Bruce works at Neiman Marcus and is Celeste's loving father. A steadfast presence for his family, he shares a deep bond with his wife and daughter, though he grapples with quiet internal questions about his past.

Nick, known as "the Greek," is a charming, observant detective for the Nantucket Police. He skillfully handles interviews with the female guests, picking up on discrepancies and hidden tensions among the wedding party.

Thomas is Benji's older brother, married to an oil heiress. He benefits from the same extreme wealth as his brother but exhibits a more corrupt and self-serving attitude beneath the family's polished facade.

Abby is the pregnant wife of Thomas Winbury and an oil heiress in her own right. She is observant of the household's dynamics and fiercely protective of her position within the wealthy family structure.

Featherleigh is an antiques dealer and the sister of Tag's late best friend. She is a frequent fixture at Winbury family events, though her presence often sparks suspicion and tension among the hosts.

Chloe is a 16-year-old local resident who lost her parents at a young age. She works in hospitality and views the wealthy wedding guests with a mix of awe and perceptive distance.

Finn is Chief Kapenash's adopted son and nephew. He grows up on the island alongside his twin sister after the tragic loss of their parents.

Roger is the meticulous wedding planner managing the elaborate Summerland event. He is well-connected on the island and deeply familiar with Nantucket's high society.

Andrea is Chief Kapenash's kind and supportive wife. She provides a stable, loving home for her orphaned niece and nephew.

Travis is the predatory co-owner of the Brightstreet PR firm. His unethical actions severely impacted Merritt's professional and personal life in New York.

Cordelia is the vindictive co-owner of Brightstreet PR. She publicly badmouthed Merritt in New York PR circles following a workplace scandal.

Robin is a coworker of Bruce's at Neiman Marcus. The presence of this coworker sparked unexpected internal revelations for Bruce.

Sage is Merritt's former coworker at Brightstreet PR. She remembers the unfair treatment Merritt received from the firm's owners and provides a sympathetic view of Merritt's professional past.