Prudence Childs was once the most famous kindergartner on the planet. After teaching herself to play piano at age three, she performed at the White House, appeared on talk shows, and inspired a generation to take up lessons. But as adolescence closed in, Prudence realized that she was being exploited and pushed into fame by her cruel grandmother, so she ran away. Broke and alone, she took a job writing commercial jingles, which earned her a fortune but left her creatively adrift.

Now forty-eight, with her daughters away at school, Prudence agrees to compete on a wildly popular dueling pianos TV show to reconnect with her inner artist. Unfortunately, her new spotlight captures the attention of her terrible ex-husband, Bobby, who uses the opportunity to blackmail her over a long-buried secret. If she doesn't win, she won't just be a musical failure; she'll also be bankrupt and exposed in front of millions.

Her on-air rival, virtuoso Alexei Petrov, a young internet sensation with a massive audience and a dreamy Russian accent, has problems of his own. His demanding parents made him a technically flawless pianist but left him without friends, hobbies, or any kind of life outside his music.

As they prepare to face off onstage, the retired prodigy and the exhausted wunderkind realize that the competition is their chance to prove to their bad exes, tyrannical family members, and, most important, themselves that it's never too late to write a new ending.