There are five main characters in the film. Soha Ali Khan is a reporter in a TV Channel. R. Madhvan is a software professional in one of the MNCs. Irrfan Khan is a tea-vendor. Paresh Rawal is an elderly policeman who is going to retire soon. Lastly, K.K. Menon is an unsuccessful computer salesman.
On the D-day, Soha's fiance is killed in the bomb blast, leaving her broken. The otherwise shrewd reporter who can do anything to raise the TRPs of the channel is so traumatised by the incident and the fact the that her boss wants to exploit her situation and wants to cover a programme on her tragdey (which indeed she was also doing before she came to know that she is also being victimised).
Madhvan, a person who thinks that Mumbai can be made a better place if he doesnot use a personal vehicle and prefer to travel by train, escapes a near life threatening blast when he travels in II class and his friend loses his right hand in I class where the bomb exploded. After this incident, Madhvan is afraid of travelling in the train but is forced to travel because his wife is in labour and the taxi driver refuses to take him to the hospital because of traffic.
Irrfan Khan, a poor tea-vendor is thrown out of the mall with his family because he tried one perfume. Feeling insulted, he makes several hoax calls to the police stating that there are bombs in different malls, creating chaos among the public and the police. Due to this chaos, an elderly person suffers acute cardiac arrest and is being hospitalised. Later on, Khan realises his mistake and goes to see the old man and presents him a flower.
Paresh Rawal is an experienced policeman and knows that the system is so tangled up that one should be realistic and not idealistic in dealing with it. A junior fellow (an idealistic one) is pissed of the system but Rawal explains him from time to time to be calm. Later on, because of blasts and the junior, Rawal also realises that his thirty six years of department service is a waste as he has not done a single big thing in his career.
K.K. Menon is a hardcore hindu and thinks that every muslim is a terrorist. After the blasts, he even chased one muslim lad in suspiction. His encounter with Rawal(who has changed by now) forces him to rethink on his agenda and then he realises that there is nothing correct in hatred. Thus, he ends up in friendship with that suspected guy.
The film basically describes that the people are really fed up and terrorised by these terrorist activities but are so helpless, that they cannot stop living their lives the way they were living before the blasts. Their helplessness is often mistook as the "Spirit" of the city but in reality it is not so. It is often said that "Life doesnot stop for anybody" and "The show must go on", but seriously, people should give it a halt and rethink about the whole scenario. It is portrayed in the film in the end as all of the Mumbai pays homage to the killed by keeping silence for two minutes. The film ends up with the famous song "Aye dil hai mushkil jeena yahan, ye hai bombay meri jaan" in the background.