Thirteen-year-old Maggie O'Donnell witnesses her mother Georgina die in a car crash while saving her. She blames her father Mike and his former lover Taylor entirely for the collapse of their family. At her lowest point, an old ring left by her mother unexpectedly sends her fifteen years back in time.
As soon as she travels through time, Maggie drops out of nowhere and ruins the scene where twenty-year-old Mike is proposing to Taylor. To prove her identity, she shows documents from the future and even drags Mike to take a paternity test, which finally confirms that she is indeed his daughter from the future.
Determined to stop her mother from meeting the same tragic fate, Maggie decides to stay in the past, break up Mike and Taylor, and alter pivotal events time and again using her knowledge of what will happen. But as she spends time with her young father, she gradually realizes Mike is not the cold, defeated man she remembers. Taylor’s true colours also start to emerge. Most surprisingly of all, Maggie, who originally set out to separate her parents, ends up bringing Mike and Georgina together.
Faced with escalating retaliation from Taylor and Blair, the father and daughter trio stand united against the threats. In the end, Maggie succeeds in rewriting history and uniting her parents. When she returns to her own time, her mother is still alive, her family is whole again — and she now has a twin brother who never existed before. A brand-new future has been born.
