The film centers on Jerry (Jayasurya), a con man known for his high-stakes scams. His criminal actions create a rift in his family when he attempts to steal the family business from his sister. While planning a heist on a petrol station, Jerry helps an escaped convict, Ravi Varma (Kunchako Boban). Ravi had been caught performing similar heists with a similar con man.
Ravi Varma convinces Jerry to plan a formidable heist. An old acquaintance, Bose, tells Jerry of a forged painting that can be used to con a non-resident Indian (NRI) (Devan) out of ₹50 lakhs. The information creates a rift in the newly formed friendship as both Ravi Varma and Jerry attempt to outdo each other in order to take the money.
Coincidentally, Jerry's sister is an employee at the hotel where the NRI is staying, and both Ravi Varma and the NRI fall in love with her.
Ravi Varma and Jerry eventually lose the painting and decide to buy the original by pooling their money. They then sell it to the NRI for ₹3 crore. However, Jerry's father finds out about the plot and tells Jerry's sister, which further drives the siblings apart.
When Jerry and Ravi Varma realize that the check given to them is invalid, they fight and decide to part ways. Jerry runs into the master con man, Bose, who offers to help him resolve the situation, and takes Jerry to the wedding of Ravi Varma and Jerry's sister. Jerry learns that the entire sequence of events, starting from the gas station incident, had been completely staged as a form of gentle revenge in return for the scam that had sent Ravi Varma's father to jail.
Jerry asks for forgiveness from everyone and leaves the wedding. As the credits roll, Jerry is seen pondering another scam.Jayasurya—as Jerry Mathews
Kunchako Boban—as Ravi Varma
Charankartheek—as Super Hero
Mithra Kurian—as Saira Mathews
Nedumudi Venu—as Prabhakara Varma
Gita Nair—as Ravi's mother
Suraj Venjaramood—as ATS Shambhu
Maniyanpilla Raju—as Rangaswami
Kottayam Nazeer—as Appy Biju
Siddique—as himself (cameo)
The film was described as being similar to Fabián Bielinsky's 2000 Argentine crime drama film Nine Queens (Nueve Reinas). V. K. Prakash said: "I discovered the Nine Queens connection only after I liked the subject of Gulumaal".
Sify.com stated that "with a tighter script, better music and lesser length the film could have been even more entertaining", but added, "The best thing about the film could be its unconventional narrative style." Indiaglitz.com called it "stylish and crazy entertainment", praising the film's "intense believability" and "unstoppable flow of brilliantly witty one-liners", but criticized the poor selection of voices in Manu Rameshan's songs. VN of Nowrunning.com gave the film 2.5 out of 5, praising "the amazing camaraderie that its lead actors share" but finding fault with the "cacophony" and substandard picturization of the songs. VN also stated that Gulumal was "a straight lift off the Argentinian film Nueve Reinas (Nine Queens)".
The film's soundtrack contains 4 songs, all composed by Manu Ramesan, with lyrics by S. Ramesan Nair and Saimon Palvaay.