Christine is a 47-year-old amnesiac who believes she is still in her twenties. Due to a traumatic injury, she suffers from anterograde and retrograde amnesia, waking each day with no memory of her identity or past. She relies entirely on a hidden journal, her husband, and her doctor to reconstruct her reality daily. She actively questions her surroundings, searching for physical and written clues to establish her personal history.

Ben is Christine’s husband, a former architect who works as a chemistry teacher. He serves as her primary caretaker, patiently explaining her situation to her every morning using a scrapbook of photographs. He manages her daily routine, leaving instructions on a whiteboard, and actively shields her from painful aspects of her past to maintain stability.

Dr. Nash is a neurophysiologist specializing in brain disorders affecting memory. He secretly meets with Christine, taking her to locations from her past and providing her with a journal to record her days. He is highly interested in her rare condition and plans to write an academic paper documenting her progress.

Claire is Christine’s closest friend from her university days. She was once an aspiring artist who brought energy and loyalty to Christine's early life. Now homeschooling her young son, she remains a crucial source of support and objective truth regarding Christine's life before the memory loss.

Adam is Christine and Ben's son. Though Christine struggles to remember him clearly, the knowledge of his existence creates a profound emotional anchor for her. His history forms a central piece of the puzzle Christine attempts to solve regarding her family.

Mike is a figure from Christine's past who becomes significant as she pieces together fragments of her previous life. He is tied to events that occurred before her memory loss, representing a hidden chapter of her history.

Dr. Wilson is a medical professional at the psychiatric ward where Christine lived for seven years following her attack. She maintains the records and diaries from Christine's early, highly disoriented days of amnesia, introducing the concept of confabulation.

Toby is Claire's young son. He has ADHD and requires significant attention, which leads his mother to homeschool him and pause her artistic career.

Alfie is a small boy Christine encounters while wandering alone in the park. His brief interaction with her triggers her latent maternal instincts and fantasies of caring for a child.

Helen is a young woman romantically involved with Adam. She lives with him and represents his adult life outside of his parents' immediate sphere.