Annie is a best-selling American author raised in New York by her grandfather. She grows up captivated by his stories of Ireland and ancient Celtic folklore. When she travels to Lough Gill to scatter his ashes, a mysterious event pulls her back in time to 1921. Because she bears a striking resemblance to her great-grandmother, locals assume she is the missing woman returned, forcing Annie to survive a dangerous political era while keeping her origins a secret.

Eoin is Annie's beloved grandfather who raised her after she was orphaned. In the 2001 timeline, his death from cancer prompts Annie's journey to Ireland. In the 1921 timeline, he is a six-year-old boy mourning the sudden disappearance of his mother and the death of his father in the Easter Rising. He views the newly arrived Annie as his returned mother, clinging to her stories for comfort.

Thomas is a dedicated Irish doctor who provides medical care to the Gallagher household and the surrounding community. He secretly supports the Irish liberation cause, working alongside revolutionary figures. He has spent years quietly searching for his late friend Declan's missing wife, making Annie's sudden appearance a profound shock that challenges his sense of reality.

Michael is a highly influential Irish revolutionary leader working to negotiate an end to British rule. He spearheads the movement and manages dangerous political alliances during a highly volatile time. He relies on loyal citizens to maintain momentum while facing intense pressure from both the British government and rival Irish factions.

Anne is Eoin's mother and Declan's wife who vanished without a trace during the chaotic 1916 Easter Rising. Her unresolved disappearance haunts the Gallagher family, setting the stage for their intense reactions to Annie's arrival in 1921.

Declan is Eoin's father who was killed participating in the 1916 Easter Rising. His death left young Eoin effectively orphaned and deeply traumatized his surviving family members, driving his brothers further into political extremism.

Brigid is the stern matriarch of the Gallagher family who has been raising young Eoin since his parents were lost in 1916. She is actively grieving the loss of multiple children to political violence and acts defensively to protect her remaining family. She views Annie's sudden return with critical suspicion and anger over the past.

Liam is Declan's brother and a man deeply embedded in the violent political struggles of 1920s Ireland. He harbors dark suspicions about Annie's true identity and motives, making him a consistent and dangerous threat to her safety.

Maeve is a lifelong resident of the area around Garvagh Glebe. In 2001, she is a sharp-minded elderly woman who immediately recognizes Annie's face. In the 1921 timeline, she is an earnest teenager working as household staff for the Gallaghers, experiencing the terror of British raids firsthand.

Robbie is Maeve's brother who gets caught up in the crossfire of the Irish War of Independence. His severe injury forces Annie to use quick thinking to hide him from hostile forces searching the property.

Daniel is the father of Maeve and Robbie. He works on the local estate and tries desperately to keep his family safe during the escalating violence between British forces and Irish rebels.

Ben is Declan and Liam's older brother. He is fiercely opposed to the Anglo-Irish Treaty and represents the growing, volatile divide among the Irish people regarding their political future and relationship with Britain.