This family-oriented romantic drama revolves around a joint family living in Hyderabad whose head is Ram Murthy (Nagineedu), a retired head master. He is a disciplined person and always tries to make his relatives behave in the same way. To avoid bad remarks from the society about his family, he sets up a family constitution of discipline. His obsession with discipline is such big that if any one of his family members commit 100 Mistakes, that person would be banished from the family and that mistake can be anything which Ram Murthy hates which ironically includes laughing out loudly.
Thus all of the family members maintain a disciplinary life to avoid being banished from the house. In detail, the family consists of Ram Murthy's wife Seetha, an Asthma patient; his daughter Kasthuri, his son in law Anand and their kids. Apart from them are Ram Murthy's two sons Brahmaji (Brahmaji) and Sundeep (Sundeep Kishan). Since Ram Murthy's brother Subrahmanyam (Prithviraj) was alleged to be committed 100 Mistakes though he didn't, he is sent away from home.
While all of the family members commit mistakes less than 20, Sundeep commits 99 Mistakes and one more, he is out of the family. So to avoid that Sundeep starts leading a careful life. Brahmaji's marriage is scheduled at Tirupathi and the whole family boards Venkatadri Express at Kacheguda. Sundeep's mother forgot the Mangala sutra at the house and Sundeep goes away to bring it back.
Moreover to his convenience, Sundeep is in S4 while others are in S3. So Sundeep goes outside the station and waits for an Auto-Rickshaw, But none accepts to go to his area. Meanwhile a miser techie Prarthana (Rakul Preet Singh) reaches Kachiguda railway station to board the Venkatadri Express and the Auto-Rickshaw driver goes to bring the change in order to pay her off the balance amount after receiving the fare.
Sundeep gets into the vehicle and goes to his home. He breaks the house's lock with a stone as he has no keys to open it. He takes the Mangala sutra and goes back to Kacheguda Railway Station. Prarthana catches yet another auto and reaches to the station. There she pays off the fares of both the vehicles and goes to board the train.
Meanwhile a passenger Dasthagiri (Sapthagiri) asks Sundeep to take care of his bag till he gets into the train after buying a water bottle and Sundeep accepts it. They both save each other's Mobile numbers so that Sundeep can give a missed call to Dasthagiri if the train leaves the station and due to that, Dasthagiri would board the train. However a tiffin vendor and a customer quarrel. Sundeep in order to avoid committing the 100th mistake keeps quiet.
The story shifts to next day morning around 9:30 in the Morning at Tirupathi Railway Station. Ram Murthy and his entire family travel in two cars which are led by two baaraat bands. Ram Murthy, Seetha, Kasthuri and her younger son travel in one car and Sundeep, Brahmaji, Anand, Anand's son Nikhil and their servant travel in another car. Sundeep's shirt has Blood stains and when Anand, Brahmaji ask the reasons for the stains, Sundeep narrates the story which happened in the past 12 hours.
To compromise and stop a quarrel, Sundeep gets down from the train and starts speaking with the aggrieved persons. Prarthana misguides the customer that Sundeep is a Robber and goes along with the customer to complain on Sundeep. Meanwhile Sundeep is thanked by the tiffin vendor. But to Sundeep's misfortune, Venkatadri Express leaves the platform.
So with the help of the tiffin vendor's friend and goods transporter Audi short for Anand D (Thagubothu Ramesh), Sundeep goes to Shadnagar. While Sundeep reaches Shadnagar, Audi goes to the nearby Bar and quarrels with the local police calling their brandy as cheap liquor. Sundeep saves Audi in time only to realize that the vehicle's keys are in the Bar. Yet again Audi insults the police. In the meanwhile time Sundeep is informed by Dasthagiri that Train left Shadnagar and is heading towards Jadcherla.
Sundeep and Audi unknowingly get into a car and drive away to Kurnool in order to catch the train. However once again to Sundeep's misfortune, They robbed the Police's vehicle and the police are following them. They leave the car and reach the station of Kurnool. A Drunken Audi gets into Venkatadri Express making Sundeep miss the train again. In the process Sundeep gets hurt and faints. On gaining consciousness, Sundeep is shocked to see that he is been taken to Shadnagar police station by those Police.
Yet again Sundeep escapes and hangs on a Private Bus. The Bus stops and Sundeep gets into it for travelling to Dhone Junction, yet another important stop of Venkatadri Express. To his shock Prarthana is his co-passenger. Both unnecessarily quarrel and hence are forcibly dropped out from the Bus.
They board a car whose Tyre gets punctured. Sundeep goes away with the Tyre telling that he would get it repaired but inturn reaches Dhone Junction Railway Station. Yet again luck misfires and he boards the Venkatadri Express which goes from Tirupathi to Kacheguda. He gets down from the train in time and goes to the next platform to board the Venkatadri Express which goes to Tirupathi. But he couldn't go as he forgot the Bag of Dasthagiri and more to it Prarthana reaches to Dhone Junction with the bag only to stop Sundeep from boarding the Train.
Sundeep in agony slaps Prarthana and yells at her that he needs to reach Tirupathi in time. Prarthana too responds rashly that Sundeep too left her on a highway without any mercy at midnight not even thinking about her safety. Both come to an Understanding later and travel. In the mean way while Sundeep is away for a nature call, Prarthana is kidnapped by some men for a forcible sexual intercourse with her luckily Sundeep reaches in time and rescues her. Sundeep and Prarthana flee away using one of the goon's bikes and reach Kadapa next morning.
Venkatadri Express was said to be late for 2 Hours. In the balance time, Sundeep narrates his whole story to Prarthana who now understands his situation. At the railway station Sundeep and Prarthana save two eloped lovers from the henchmen of the girl's father. They escape from the railway station and with the help of a Thrill seeking Cab owner Bhadra (M. S. Narayana), Sundeep conducts the lovers' marriage and gives away the Mangala sutra which he has to give to his brother.
Brahmaji is furious after listening this but after that Sundeep shows yet another Mangala sutra and continues the story. After the happy ending of the lovers' marriage, Sundeep and Prarthana are worried about the future consequences and are just 15 km away from Tirupathi. But Dasthagiri informs them that Venkatadri Express is scheduled to arrive in nearly 10 minutes. Now they find that Subrahmanyam is a lorry driver who gave them lift to reach the station.
Subrahmanyam is a bachelor who dreamed to get married and he gives away the Mangala sutra he purchased. Sundeep reaches on time and boards the train just before it stops in Tirupathi Railway Station. He acts as if though he was sleeping and the rest happened. Now the marriage of Brahmaji is being conducted and Prarthana, Subrahmanyam attend the marriage.
The bride's father (Jaya Prakash Reddy) is in worry as the bride eloped with her lover and his men are searching for her. To the shock of Sundeep, the bride is none other than the girl whose marriage was conducted by him and Prarthana at Kadapa. Now Ram Murthy comes to know that the girl eloped with her lover and the marriage is halted.
Seetha comes to know the fact that the girl's marriage was conducted by Sundeep and gets a severe Asthma attack. She is joined at the Government Hospital. When Seetha was taken to the Hospital, the bride's father comes to know about Sundeep's act by his henchmen and is furious. In the chase, Brahmaji comes to know the fact and Audi who reached Tirupathi in Venkatadri Express is following the chase.
During the chase, Ram Murthy lets Sundeep escape Red Traffic Signals and a Traffic Constable is hurt by them. After she is admitted into the Hospital, Sundeep fights with the bride's father's henchmen and Ram Murthy doesn't stop him from doing so. Later Ram Murthy comes to know the truth and Sundeep's mistakes turn 100. Sundeep then reminds that Ram Murthy broke his Discipline and ideals during the chase and the fight and he can't leave the family because what he did was just helping the ones in need.
The bride's father accept the Lover's marriage. Ram Murthy increases the Mistakes level from 100 to 1000 letting Sundeep and Subrahmanyam re enter the house. Seetha is discharged immediately. Audi joins the family as a servant. The film shifts to 3 months later on the day of Brahmaji's engagement at Ram Murthy's house. Brahmaji orders his servant to show his would-be to Sundeep first in order to avoid the previous incident.
Audi leaves Drinking and keeps on working there. Dasthagiri comes to meet Sundeep as because of him, Dasthagiri was restless on that day and thus appeared very tiresome at the Tirumala Tirupati Devasthanams interview which made the selectors think that he studied well prompting them to appoint him. Sundeep is terrified and tensed and when his lover Prarthana asks him the reason, he replies in a tense manner that he committed his 999th Mistake.