A spate of gruesome bucket‑killing murders sweeps the city, baffling the local police. When the investigations stall, a specialised CBI team led by senior officer Sethurama Iyer steps in, determined to untangle the unprecedented, never‑before‑seen mystery behind the killings.
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Read the complete plot breakdown of CBI 5: The Brain (2022), including all key story events, major twists, and the ending explained in detail. Discover what really happened—and what it all means.
Aparna is an IPS trainee who leaves her home to attend a seminar hosted by the CBI for IPS trainees. Malavika Menon plays Aparna, and the session is led by DSP Balagopal Renji Panicker and Inspector Vinay Ramesh Pisharody. As the two officers discuss several cases the CBI has handled, they revisit a notorious string of murders known as the Basket Killings, a case that the senior CBI officer Mammootty Sethurama Iyer once cracked. The seminar quickly turns into a deep dive into a tangled web of political power, medical intrigue, and lethal ambition.
The central thread revolves around the mystery that began in October 2012, when Abdul Samad, the Home Minister of Kerala, dies while traveling from Delhi to Nedumbassery. Some chalk it up to natural causes, but whispers grow louder as Samad’s doctor, Dr. Venu Pradeep Menon, also dies under suspicious circumstances. Protests erupt, with journalist Bhasuran Chandhunadh spearheading calls for a full investigation. Soon after, Bhasuran is found murdered by hanging, and Josemon Jayakrishnan – a cop with a routine morning walk – is killed when a vehicle runs him down. The police see a pattern and label the killings as part of a broader conspiracy tied to a shadowy name: Mansoor.
As the case unfolds, DYSP Sathyadas Saikumar enters the scene, a corrupt officer who openly distrusts the CBI and particularly dislikes Iyer. The investigations stall until a petition is filed in court to transfer the case to the CBI, which slowly gains traction thanks to pressure from Josemon’s family and a counter-move from the CBI itself. Adv. Prathibha Sathyadas Asha Sarath, Sathyadas’s wife, appears to have her own motives in steering the petition toward a resolution. The pursuit of truth weaves through both legal and clandestine channels, until Iyer and Balagopal manage to secure a fresh directive from the CBI Director to take over the case from Kerala’s side and bring it to New Delhi for a thorough review.
Iyer’s team discovers that Samad and the Chief Minister had once discussed a youth named Mansoor, a relative of Samad who had joined a militant group years earlier. The inquiry shifts to Sam and his connections, including his links to Adv. Prathibha and Dr. George Prathap Pothan. The trail grows colder when Sam is found dead after a hospital escape, a mystery that deepens when Meyjo – also known as Paul Meyjo – re-enters the picture. A man with a pacemaker design that could potentially be hacked, Meyjo Soubin Shahir reveals a chilling capability that he claims only serves to prove a point about the vulnerability of modern medical devices. Yet the authorities lack enough evidence to keep him detained, so he is released.
The investigation then points toward a complex plot surrounding Dr. Venu’s patient, Susan George Kaniha, who was formerly known as Ambika Unnithan. Meyjo, while undercover, is connected to a web of relationships that includes the ex-wife of Iyer’s ally, Dr. George’s wife and the mystery of Susan’s true identity. When Iyer learns that the apparent murder of Samad might have been a setup to target Susan, the stakes rise sharply. Meyjo, having moved through a priestly disguise, is captured near a beach, and interrogations reveal that the killer’s motivation is not simple vengeance but a calculated scheme tied to multiple players, including Sam and Unnithan who manipulated events from behind the scenes.
A crucial breakthrough comes when a torn newspaper clipping found in Meyjo’s Bible reveals a photo that identifies Susan. Iyer stays with Susan to uncover her backstory, including the fact that she had once been Ambika Unnithan, the estranged wife of Anoop Menon as I.G. Unnithan. The investigation uncovers a terrifying sequence: Meyjo killed Abdul Samad on orders from Sam himself and from Unnithan, who was tormented by paranoia and suspected abuse toward his wife. The motive appears to be a plan to silence Susan and to eliminate Dr. Venu, who had begun to unravel Meyjo’s true intentions.
As the pieces fall into place, Bhasuran’s murder is connected to the protests that sought to expose the truth, and Josemon’s death is reinterpreted as the consequence of collusion. The trail leads Iyer to Unnithan’s door, where he uncovers a critical piece of evidence: a newspaper clipping confirming the conference between Unnithan and Meyjo to carry out the plan to kill Susan. Unnithan is arrested, and his trial ends with him collapsing from a heart attack before justice can take its full course. The film’s closing arc follows Iyer visiting the prison where Meyjo remains a constant shadow, warning that Iyer himself is Meyjo’s next target. The final moments leave Iyer reflecting on Vikram’s fate and the labyrinthine reach of those who bend law and morality to serve their ambitions, as Meyjo’s chilling warning hangs in the air.
The case, with its political entanglements, medical ethics questions, and labyrinthine conspiracy, underscores a single truth: power can corrupt everything, and truth can be elusive even for seasoned investigators. The narrative balances procedural detail with character-driven drama, painting a meticulous portrait of an elaborate scheme where every murder, every alibi, and every confession is a carefully placed piece in a much larger puzzle that only the most relentless investigators can hope to solve.
Last Updated: October 01, 2025 at 10:23
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