The Indian Navy decodes a secret code sent from Pakistan to then-East Pakistan (modern-day Bangladesh) and intelligence report of a Pakistan Navy's submarine called PNS Ghazi, a much more advanced submarine than ''INS Karanj (S21)'' or any other Indian submarine, being sent through the Bay of Bengal under the command of Commander (rank) Razak Khan (Rahul Singh (actor)). The top command dispatches ''S21'', a submarine, under the command of Captain (Royal Navy) Ranvijay Singh (Kay Kay Menon) for surveillance. To temper Singh's belligerent tendencies, the Indian Navy Admiral assigns Lieutenant commander (Royal Navy) Arjun Varma (Rana Daggubati), with orders to ensure that Singh does not confront any Pakistani warships and trigger a war.