In ancient India, a group of sages in the Himalayas collide with the energy Brahm-shakti, which produces many celestial weapons of great power called astras. The strongest among them, the Brahmastra, has the capacity to destroy the world. The sages use their respective astras to tame the unstable Brahmastra and become the Brahmansh, a secret society to protect the world from the powers of astras.In present-day Mumbai, Shiva, a disc jockey, falls in love at first sight with Isha Chatterjee, a London resident who is visiting India for the Durga Puja festival at her grandfather's pandal. Soon, Isha reciprocates and expresses her feelings for Shiva. Shiva tells her that he is an orphan who never knew his father, and that his mother died in a fire when he was a baby (1993).Meanwhile, in Delhi, scientist and Brahmansh member Mohan Bhargav is attacked by Zor and Raftar for a piece of Brahmastra he safeguards. Mohan fights back using the Vanarastra but is ultimately subdued by Junoon, who works for the mysterious evil named Dev. Under Junoon's possession, who was using Vash Mukut, Mohan reveals that the second piece of Brahmastra is protected by an artist and archaeologist named Anish Shetty in Varanasi. Before he can reveal the current location and guru of the Brahmansh (Ashram), Mohan throws himself out of a balcony.Shiva has a vision of Mohan's encounter with Junoon, as she has a piece of Agneyastra tied to her one hand, and Shiva is somehow connected to it. He and Isha head for Varanasi to warn Anish but are interrupted by Raftar, who now wields Mohan's Vanarastra. Anish defeats him using the Nandi Astra before escaping with Shiva and Isha. While going to Himachal Pradesh, where Ashram is located, they are chased by Junoon and Zor in a truck. Anish gives the second piece of the Brahmastra to Shiva and stays to fight Junoon and Zor, only to be killed. Shiva and Isha are chased by Raftar to Ashram where Shiva kills him using his power of fire after he tried to kill Isha. At Ashram, they learn about other astras and Shiva is forced to join Brahmansh by the guru Raghu for information on his parents. He meets other new recruits Rani, Raveena, Sher and Tenzing, who are all trained by Raghu on how to use their respective astras and Shiva also gains control over fire. As Junoon gets closer to them, Raghu reveals that Shiva is the son of former Brahmansh members, Dev and Amrita. Dev actually awoke the Brahmastra as he was the only person who was able to control multiple astras at once.Dev's wife Amrita (pregnant with Dev's child), who wielded the Jalastra, defeated Dev in a battle on a remote island and both of them seemingly perished in the battle. Amrita's boat was found in the ruins of the battle, brought back from the island, with two broken pieces of the Brahmastra. The pieces of the Brahmastra were given to both Mohan and Anish. The third piece was believed to be missing, with Raghu and Shiva concluding that they both survived the battle. The third piece of the Brahmastra is in Amrita's Mayastra disguised into a conch shell, which Raghu releases by dropping Shiva's blood on the conch. Junoon and her army arrive at Ashram for the Brahmastra and hold everyone hostage. Shiva defeats Junoon while also killing Zor, who wielded Anish's Nandi Astra and releases everyone. But Junoon manages to take the third piece from Isha. She seemingly sacrifices herself to activate the Brahmastra. The destruction begins and Isha is in danger, but Shiva gains control over the Brahmastra with newfound strength stemming from his protectiveness of Isha and reunites with her.Before the credits, due to Junoon having activated the Brahmastra, Dev, who was imprisoned as a statue on an unknown island, is released.