The film is based on the Indian version of the navy's attack on Pakistan's submarine Ghazi that sunk near Visakhapatnam. Following intelligence reports that Pakistan is planning to attack one of India's ports, an S-21 submarine is sent into the sea.

Led by Capt Ranvijay Singh (Kay Kay Menon), officer Devaraj (Atul Kulkarni) and Lieutenant Arjun (Rana Daggubati), the submarine begins a classified search mission.

The Pakistani submarine Ghazi comes close to East Coast of India to target INS Vikrant. How S-21 submarine attacks Ghazi and sinks it forms the rest of the story.