Shekhar & ex-army doctor Jayavrat Saini team up to solve a series of murders in Lonpur marked by a "horse shoe" symbol. As Jayavrat evolves from roommate to partner, a shadowy figure known as "M" ominously watches Shekhar from the shadows.

Shekhar dives into a village scam where a jungle adventure leads to a bank heist. With a bride-to-be's father missing, he uncovers a tangled plot revealing a cunning robber with a grudge, while the looming threat of "M" draws ever closer.

Iraboty's arrival in Lonpur sparks intrigue as she convinces Shekhar to investigate the 150-year-old Skhondokhata legend in Purulia, linked to recent deaths in the Bhaskar family. Shekhar suspects a deeper conspiracy.

Mrs. H & Pintoo are held hostage at Khasha Blanca forcing Shekhar to confront his past where he had uncovered a deadly gas weapon linked to M, a criminal mastermind. Now they must find the vial or his friends lose their lives.

Racing against time, Shekhar and Jayavrat hunt for clues across Calcutta left by the scientist Gupta, aiming to find a vial with the secret gas formula. As they near the final code, Shekhar faces M in a deadly struggle.