Tashi Duncan (Zendaya), a former teenage tennis phenom is now a coach. She's taken her husband, Art (Mike Faist), and transformed him from a mediocre player into a world-famous grand slam champion.

To jolt him out of his recent losing streak, she has him play a "Challenger" event — close to the lowest level of tournament on the pro tour — where he finds himself standing across the net from the once-promising, now burnt-out Patrick (Josh O'Connor): his former best friend and Tashi's former boyfriend. Tensions run high on and off the court as old flames are reignited, competition builds, and love and careers hang in the balance; it's anyone's game.