Bhairava, tired of the oppressive confines of his homeland and the perilous life of a bounty hunter, yearns for a more comfortable existence in the Complex. His quest for a new life inadvertently entangles him with a group of rebels dedicated to freeing humanity from the grip of malevolent forces.

In 3102 BC, following the Kurukshetra War, Ashwatthama attempts to kill Uttarā's unborn child by invoking the Brahmashirastra. For this act, Krishna curses him to roam the earth as an immortal. His divine gem is also taken from his forehead, and his redemption is destined to occur through protecting and guiding Vishnu's last avatar, Kalki, during the Kali Yuga.

By 2898 AD, six thousand years into the Kali Yuga, the desertified city of Kasi stands as the last known city in a post-apocalyptic world dominated by Supreme Yaskin, a totalitarian god-king. Yaskin rules from the "Complex", an inverted-pyramidal-megastructure that hovers above the city, extracting Earth's resources to sustain a gated paradise accessible only to those who can pay 1 million "units". His authority is enforced by Commander Manas, Counsellor Bani and the Raiders, who vigilantly guard against threats, particularly the prophesied arrival of Kalki.

In this dystopian society, fertile female refugees in Kasi are forcibly taken to the Complex for Project K, an experiment aimed at producing a life-extending serum for the 200-year-old Yaskin through artificially inseminated foetuses. However, no woman survives more than 120 days of pregnancy, resulting in their deaths. Raia, a young girl disguised as a boy, narrowly escapes conscription with the help of rebels led by Rumi from the hidden city of Shambhala. Unfortunately, Rumi and Divya, falsely rumoured to be pregnant with Kalki, are captured and executed in public by Manas for not revealing Shambhala's location.

Raia finds refuge in a cave, where she encounters Ashwatthama. She unknowingly brings him his divine gem, Shivamani, from the Shambhala rebels. Together, they set out to find the real mother of Kalki. SUM-80, a Project K subject hiding her 150-day pregnancy, is eventually captured. Manas extracts a drop of serum from her foetus, but the procedure is interrupted by Lilly, a Shambhala rebel posing as a Project K subject. Lilly helps SUM-80 escape, but stays behind to fight off the Raiders. Outside, they are met by other Shambhala rebels: Veeran, Kyra, and Ajju. Kyra renames SUM-80 as "Sumathi". En route to Shambhala, their convoy is ambushed by bounty hunters and Raiders after Manas places a bounty on Sumathi. Though they fend off the attackers, Kyra is killed.

Bhairava, a bounty hunter aiming to secure Sumathi's bounty to enter the Complex, remains in pursuit with his AI supercar, Bujji. Ashwatthama learns through his gem that Sumathi’s unborn child is Kalki. Despite Bhairava's efforts, Ashwatthama subdues him and the group reaches Shambhala, where the tree of life blooms in recognition of Kalki's presence. Bhairava makes a deal with Manas to capture Sumathi in exchange for his entry into the Complex.

Bhairava discovers Shambhala by deceiving a spy, Luke, and disguises himself as Ashwatthama by using his hologram technology. He convinces Sumathi to flee Shambhala, but they are intercepted by the real Ashwatthama. As they fight, Shambhala's leader, Mariam, takes Sumathi away. Bhairava, overpowered by Ashwatthama, transforms Bujji into a humanoid fighter but is again defeated. Manas and the Raiders track Bhairava to Shambhala and breach its defences with a beam weapon provided by Yaskin. The Raiders overwhelm the Shambhalan army, and Mariam is killed. Manas chains Ashwatthama, but Bhairava, wielding Ashwatthama's walking stick, which is actually revealed to be Karna's bow, Vijaya Dhanush, awakens and attacks the Raiders.

Bhairava, who is revealed to be a reincarnation of Karna, uses the bow's power to rescue Sumathi and kill Manas. Ashwatthama, recognising his old friend, breaks free, but Bhairava, reminded of the bounty by Bujji, reverts to his former self and takes Sumathi away. Back at the Complex, Yaskin, informed of Manas's failure and death by Counsellor Bani, uses the extracted serum drop to transform into a youthful superhuman with multiple arms. He picks up Arjuna's bow, Gandiva, and declares his intention to personally capture Sumathi and her son and reshape the world.