The story follows the life of Rohit Mehra (Hrithik Roshan), a scientist, and Krishna Mehra a.k.a. Krrish (Hrithik Roshan), his superhero son, who face an elaborate conspiracy orchestrated by the evil genius Kaal (Vivek Oberoi) and his female accomplice Kaya (Kangana Ranaut). In the process, Krishna's pregnant wife Priya (Priyanka Chopra) is kidnapped by Kaal and the form-changing Kaya takes her place at the Mehra home and eventually falls in love with Krishna.