SHERSHAAH is the story of a brave Indian soldier who laid down his life during the 1999 Indo-Pakistan war. Vikram Batra (Sidharth Malhotra) stays with his parents in Palampur, Himachal and his twin brother, Vishal Batra. Since the time he was a child, he was interested in joining the army. At college, he meets Dimple (Kiara Advani) and falls for her. She reciprocates his love and both start a relationship. At this point, Vikram decides to join the merchant navy instead of the army as it pays better. One day, when Vikram drops Dimple home, Dimple's father (Bijay J Anand) catches them red-handed. He tells Vikram that since he belongs to a different caste, he can't marry Dimple.
Dimple, however, protests and even tells her father that Vikram would earn more than him since he's going to join the merchant navy. Meanwhile, Vikram starts getting second thoughts after his best friend Sunny (Sahil Vaid) insists that he should not give up his dream of joining the army. Vikram tells Dimple about his change of plans. This infuriates Dimple and she requests him not to make any more changes in future plans. Vikram then enrols himself at an army institute and passes with flying colours. In 1998, he gets his first posting at 13th Jammu and Kashmir Rifles at Sopore.
Vikram is now a Lieutenant. His regiment comprises Lieutenant Sanjeev Jamwal (Shiv Panditt), Naib Sudebar Bansi Lal Sharma (Anil Charanjeett), Subedar Raghunath (Raj Arjun), Major Subrata Mukherjee (Abhiroy Singh) and Major Ajay Jasrotia aka Jassi (Nikitin Dheer), etc. In no time, Vikram proves his worth when he manages to capture a dreaded terrorist, Attaullah (David Browne), who's a part of the gang of an evil militant, Haider (Mir Sarwar). Vikram also befriends locals, unlike other soldiers. This proves to be of great help as a friendly local, Gafoor (Zahoor Zaidi), informs him that his son Arslaan (Afnan Ashia) has joined Haider's gang but wants to leave them.
Meanwhile, Haider attacks 13th Jammu and Kashmir Rifles while they were moving as an act of revenge for capturing Attaullah. Naib Sudebar Bansi Lal Sharma loses his life in this attack. Arslaan helps Vikram as he tells the latter about Haider's hideout. In a risky operation, Vikram leads his team to the hideout and manages to capture and eliminate Haider. Before his death, Haider however warns Vikram that something big and devastating is going to happen soon. What happens next forms the rest of the film.