Kate is a 40-year-old widow and single mother living in Canberra, Australia. Following the tragic loss of her husband to early-onset Alzheimer's, she struggles to manage her daily life and maintain her job in a university fundraising department. She is fiercely devoted to her five-year-old son, Charlie, but feels her own identity has been entirely consumed by her grief.

Hugh is the organized, highly capable head of the fundraising program at the university where Kate works. He is profoundly principled and keeps a careful emotional distance from most people. Despite his reserved exterior, he is constantly available to help Kate manage her crises, acting as a steady, reliable force in her chaotic life.

Cameron is Kate's late husband and the father of Charlie. Previously a highly respected professor of medieval literature, his life was cut tragically short by rapid, early-onset Alzheimer's disease. He was a deeply devoted and loving husband who wrote notes to help Kate and himself as his memory faded.

Grace is Kate's forthright, fun-loving best friend in Canberra. She actively helps Kate manage childcare for Charlie and tries to pull Kate out of her grief. Grace is dealing with her own private struggles, specifically facing a diagnosis of poor ovarian reserve and aggressively seeking a path to motherhood.

Charlie is Kate and Cameron's five-year-old son. He is described as a miniature version of his father. Innocent and energetic, Charlie is the center of Kate's world and her primary motivation for keeping her life together following Cameron's death.

Justin is an attractive new neighbor who rides a motorcycle. He inadvertently causes a stir when he arrives just as the police are called to deal with a defunct grenade in Kate's house. He provides a brief, exciting distraction for Kate when her car battery dies.

Genevieve is a woman from Hugh's past who holds significant emotional weight in his life story. Her history mirrors Kate's own experiences with grief, providing an unspoken parallel between the two women.

Ruby is a young woman whom Kate occasionally spots spending time with Hugh. Her presence initially causes Kate to misinterpret the nature of Hugh's private life before Kate learns about Ruby's ties to Genevieve.

Andrew, who goes by Jonesy, is an old university friend of Hugh's. He runs into Hugh and Kate in Ballina, providing Kate with unexpected insight into Hugh's guarded past.

Sophie is Kate's coworker at the university. She acts as a sounding board in the office and provides outside perspective on how highly the staff regards Hugh.

Max is Grace's former boyfriend of ten years. He left her after repeatedly promising they would start a family together. This abandonment sparks Grace's urgent quest to find a sperm donor and become a mother on her own terms.