Lincoln is a 66-year-old commercial real estate broker living in Las Vegas. He inherited a house on Martha's Vineyard from his mother and travels there for a reunion with his two college friends. Coming from a background with a domineering father, he struggles with his own identity and financial concerns following the 2008 financial crisis. He acts as the pragmatic organizer of the group.

Teddy is a 66-year-old small-press publisher operating out of Syracuse. He is a solitary, intellectual man who suffers from periodic mental health crises he calls "spells." A high school basketball injury left him with a severe spinal condition that continues to affect his self-image and relationships. He approaches the reunion with caution, fearful that the memories will destabilize him.

Mickey is a 66-year-old working-class musician from West Haven, Connecticut. He maintains a boisterous, easygoing exterior that anchors his friendship with Lincoln and Teddy. Having faced a low number in the 1969 draft lottery, Mickey carries the weight of past decisions related to the Vietnam War. He rejects the trappings of upper-class mobility, preferring a life rooted in his music and personal loyalty.

Jacy is a wealthy, spirited young woman from Greenwich who forms an unlikely bond with three working-class men during their college years. She serves as the fourth member of their close group, defying the social expectations of her upper-class peers. Her sudden disappearance following a 1971 weekend at Martha's Vineyard leaves a lasting void in her friends' lives.

Dub-Yay is Lincoln's father, a domineering mine owner from Arizona. He adheres to a rigid, patriarchal worldview and often belittles his son's choices, including mocking his college friends with derogatory nicknames. His overbearing nature casts a long shadow over Lincoln's adult life.

Trudy is Lincoln's mother, a woman who maintains a quiet resilience in the face of her husband's domineering personality. She deeply values the freedom associated with her East Coast background. Her sole ownership of the Chilmark house represents her private rebellion against her husband's control.

Anita is Lincoln's wife, offering a stable and pragmatic presence in his often tumultuous internal life. She stays connected with him through phone calls during his trip, providing practical advice and helping him recall forgotten details about his youth.

Joe is a retired police chief on Martha's Vineyard who originally investigated Jacy's disappearance. He is a cynical, world-weary man dealing with declining health and family estrangement. His harsh worldview frequently challenges Lincoln's optimistic assumptions about the past.

Mason is the ornery, aggressive neighbor adjacent to the Moser property on Martha's Vineyard. He has a history of inappropriate behavior and serves as a persistent antagonist to the three friends—both during their college years and in the present day. He is eager to purchase Lincoln's land to secure property access.

Delia is a young woman with distinctive purple hair who performs as a singer. She has recently connected with Mickey and joins him in the local music scene. Struggling with opioid addiction, she is looking for stability and a sense of purpose.

Vance is Jacy's college fiancé, hailing from a wealthy, upper-class background. He represents the elite social hierarchy of Minerva College and expects to seamlessly step into a privileged life. Following Jacy's disappearance, his grief manifests as aggressive entitlement.

Theresa is a former college president who helped Teddy found Seven Storey Books. She maintains a steadfast friendship with him despite his emotional distance. She represents a missed opportunity for connection in his isolated life.

Donald is the man who raised Jacy in Greenwich. He maintains a facade of wealthy respectability while closely controlling his household dynamics. His presence heavily influences Jacy's desire to escape her family life.

Vivian is Jacy's mother, a woman who prioritizes social standing and family secrets over emotional honesty. She is complicit in the strict, often harmful dynamics of the Calloway household in Greenwich.

Martin is Lincoln's realtor on Martha's Vineyard. He provides essential practical information regarding property lines, easements, and local reputations, helping Lincoln plan the potential sale of the Chilmark house.

Beverly is a newspaper staffer who assists Lincoln with the microfilm archives. She is deeply embedded in the local community and manages complicated family ties on the island.

Christine is the president of the Theta sorority house at Minerva College. She acts as an enforcer of the school's social hierarchy and openly disapproves of the scholarship students working in the cafeteria.