The recently dismissed police commissioner of Chennai, Maraar (Mohanlal) describes in a voice-over about his sudden termination due to a common man who walked into his life. An unnamed man (Kamal Haasan) is shown strategically placing a travel bag in a train in the Chennai Central railway station and in a shopping mall. He proceeds to place another bag, under the pretence of lodging an First Information Report, in the toilet of a police station in Anna Salai, Chennai. He then arrives on the rooftop of an under-construction building and sets up his base of operations, equipped with gadgets and instruments. He calls up Maraar and informs him that five bombs have been planted in locations throughout Chennai, which are programmed to explode simultaneously within four hours.