Rhiannon is a high school teenager who finds her world turned upside down when she meets a mysterious person named "A." inhabiting different bodies every day. One day, A wakes up in the body of Rhiannon's boyfriend, Justin, and they spend an unusually perfect day together. When Justin reverts to his usual self, Rhiannon is left puzzled about the sudden change in his behavior. Soon after, A reveals their secret to her: they are a soul who wakes up each day in a different person's body, living out that day in their place. Despite the bizarre nature of A's existence, Rhiannon finds herself drawn to them emotionally and starts to develop feelings.

As Rhiannon grapples with this revelation, she struggles to maintain her relationship with A while dealing with the complexities of her daily life and the unpredictability of A's condition. The pair tries to find ways to maintain their connection despite the daily changes in A's appearance and identity. Meanwhile, Rhiannon faces pressures from her family and friends, who are unaware of her secret relationship. Amid these challenges, she must decide whether she can truly accept and love someone whose life is so transient and uncertain. The story follows the emotional journey and moral dilemmas that Rhiannon faces as she navigates this unique and ever-shifting bond.