MMA trainer Sienna thinks that she and her champion boyfriend Jax are the perfect team. That is, until the day she discovers him cheating on her with her own sister. Bent on revenge, Sienna starts training the one man capable of dethroning Jax: his arch-nemesis Kayden. What begins as payback quickly turns into something much more heated as boundaries are blurred and workouts get steamy. Based on the wildly popular novel by Claudia Tan.