Meredith is a young woman struggling to process the death of her older sister, Claire, who died in a car accident a year and a half ago. She has spent the intervening time isolating herself from her extended family and her childhood friends. Arriving at her family's annual summer gathering for a cousin's wedding, she resolves to honor her sister's memory by winning the traditional family game of Assassin.

Stephen, who goes by his nickname "Wit," is a student at Tulane University and the stepbrother of the groom. He arrives at the wedding week sporting a bruised face from his initial encounter with Meredith. Attentive and adventurous, he quickly becomes a confidant to Meredith and agrees to an intelligence-sharing pact for the family game.

Claire is Meredith's older sister who passed away a year and a half before the family gathering. Though she is gone, her presence is felt heavily throughout the family estate on Martha's Vineyard. She was known for being fiercely competitive, particularly as the reigning champion of the family's Assassin game, and her absence leaves a massive void for her relatives.

Ben is Meredith's former boyfriend who ended their four-year relationship just two weeks before the family gathering. Despite initiating the breakup, he continues to contact her, offering unsolicited compliments and suggesting he should have accompanied her to the wedding. He represents the isolated period of Meredith's life following her sister's death.

Sarah is Meredith's cousin and the bride-to-be whose wedding brings the family back together at Martha's Vineyard. She bears a striking physical resemblance to Claire, which occasionally startles Meredith. As she prepares for her wedding, she also navigates her own lingering grief over losing her favorite cousin.

Michael is Sarah's college sweetheart and fiancé. He is integrating into the large Fox family and enthusiastically participates in their traditions, including helping to organize the massive game of Assassin for the wedding guests.

Luli is a childhood friend who spends summers at the Vineyard with the Fox family. She is deeply hurt and resentful that Meredith ignored her messages for a year and a half after Claire's death. She expects an apology and an explanation for the abandonment.

Wink is Meredith's grandfather and the patriarch of the Fox family. He serves as an authoritative but gentle figure during the family gathering, occasionally acting as a referee for disputes during the game of Assassin and offering quiet guidance to his grandchildren.

Honey is the matriarch of the Fox family and Meredith's grandmother. She helps host the massive gathering at the Martha's Vineyard estate and ensures that all the guests, including the groom's extended family, feel welcome.

Aunt Rachel is Meredith's heavily pregnant aunt. She practices daily meditation to find inner peace and willingly accepts elimination from the Assassin game, knowing her pregnancy makes playing difficult.

Aunt Julia is one of Meredith's aunts attending the family wedding. She manages her young children during the chaotic family gathering and actively participates in the island-wide game of Assassin.

Jake is Luli's brother and part of Meredith's core friend group at the Vineyard. Unlike his sister, he is immediately glad to see Meredith return and welcomes her back into their summer friend circle.

Pravika is another member of Meredith's summer friend group. She quickly integrates Meredith back into their social activities, including tubing and strategizing for the Assassin game.

Eli rounds out Meredith's group of summer friends. He is happy to have Meredith back on the island and participates in the group's outdoor activities and game planning.

Meredith's mother travels to Martha's Vineyard to support her daughter and celebrate her niece's wedding. She is acutely aware of the difficulty of this trip, as it marks the first major family reunion since her oldest daughter passed away.

Meredith's father is an enthusiastic participant in the Fox family traditions. He eagerly plays the game of Assassin but sometimes forgets to account for Meredith's newfound anxiety around reckless driving.

Christine is Sarah's mother. As the mother of the bride, she is highly concerned with the aesthetics of the wedding and is upset by any disruptions to the event's perfect appearance.

Uncle Brad is an extended family member who proves to be a formidable opponent in the Assassin game, utilizing stealth to eliminate targets when they are distracted.

Ethan is Aunt Julia's young son. He provides chaotic background noise to the family gathering and occasionally leaks secrets about the game of Assassin.

Hannah is Aunt Julia's young daughter. She carries a beloved stuffed lobster around the property, which occasionally gets caught up in the older kids' antics.

Viv is a wedding guest who participates in Assassin but shows visible disdain for the game. She frequently complains about wanting to leave the island and fails to carry her target card properly.

Ian is an Assassin player who aggressively hunts his targets. His presence forces other players to change their routines to avoid being eliminated early in the week.

Wit's father is a wedding guest who accepts his elimination from the game with good humor. He has a complicated history with his son regarding attention and college expectations.