The opening scene of Nani's Gang Leader involves a bank robbery involving six people, who take up pills before executing the heist. But things go haywire when the team's getaway driver becomes greedy and decides to take the whole bounty. The consequences triggered by the casualties of the scene builds to racy procedural.

After the incident, an aged woman (played by Lakshmi) teams up with the un-usual suspects who are related to the deceased robbers in a violent bank heist. Their search to find a leader of their newly formed gang leads them to 'Pencil' Parthasarathy (played by Nani), a novelist who specializes on writing 'revenge' novels, but are basically word by word copies of Hollywood thrillers (in the introductory scene, the character is seen copying Roman Polanski's Chinatown).

Vikram Kumar's writing doesn't solely depend on the quirks of its central characters to elicit humour. There are many instances that showcases humour through inventive ideas. The narrative makes better use of Pencil's writing instincts to conjure up some of the contemplative moments. The smarter usage of 'What If' moments in the film adds more intrigue, whilst organically providing comic relief along with it.

The lack of self-importance associated with the central characters works miraculously in the comedy scenes and the film takes potshots on its own genre. There is an imaginative track that parodies the regular mass introduction scene of a motley crew in our cinema. The goofiness works because of the film's ability to mock itself. Take the scene where Pencil and one of the gang members dress up as an Anti Corruption Bureau officers in an Urban Development office. Despite fooling the officials, Pencil feels dejected because they didn't pay heed to the fake Identity card he printed.

Many gags that are inserted in the initial moments are deeply connected to the story, and seldom works as passing moments. The first half invests most of its time in picking clues from an incident. The revenge-themed film plays out like a murder mystery. The interval blocks reveals the knot that connects the clues. What follows next is a set of surprisingly pulpy twists and minor flourishes of genre-bending subversions.

The second half unfolds as a wildly entertaining cat and mouse chase between the villain and Pencil's gang. The payoff of the underdog story in the first half works well in the latter part, where they encounter setbacks. The plot thickens with character revealing moments and twists, with a fairly surprising final reveal that manages to pull the rug from beneath. However the climactic transition from being a dark comedy to an action film is a bit jarring, and the squirm-inducing comedy track involving Pencil and a bank's security officer Santoor (played by Vennela Kishore) is one of the few flaws of the film.

Gang Leader's humour work mainly due to the effortless performances of its central characters. Saranya Ponvannan is a riot as the gang-member with a penchant for making Tamarind rice, while Lakshmi's punchy one-liners adds more to the lighter tone of the film. Nani effervescent portrayal as the pulp novelist Pencil Parthasarathy completely absolves the character from the tropes of a regular commercial hero, which emerges as one of the bigger strengths. Mirosla Kuba Brojek's cinematography excels in mood creation whilst balancing the lighter tone of comedy with the stark nature of a murder mystery. Overall, Gang Leader is an unpredictable and engaging comedy.