Four good for nothing friends Roy, Adi, Boman and Manav are kicked out of their house by their landlady for not paying their rents. Desperate to earn money, they devise up a plan. Adi tells Manav to steal a painting from the house. They decide to sell it to the son of the late Businessman Dwiwedi. But, however, Manav accidentally picks up a blank painting not knowing the reality. They humorously sell the painting for Rs.20,000 to him. They then pick up the original painting with the intention to sell it to Mr. Aggarwal not knowing that he has been murdered. The case is handled by Inspector Kulkarni. He learns that before Mr. Aggrawal was murdered he was speaking on the phone to somebody and he mentioned the words 'horse' and 'grass'. He interprets these words to be some code language. Unfortunately the four arrive at Agrawal's residence. Kulkarni demands to see the painting. Seeing the horse and grass he immediately arrests them.

While travelling on the highway Kulkarni drops the four on the road after realising that they are innocent. The four are overjoyed until they suddenly witness a car accident of Don Bose. He tells them that he has hidden a treasure of 10 Crores in the St. Sebastian garden in Goa under a big 'W'. He tells them to divide the money equally among themselves and then dies. They come across Inspector Kabir Nayak who has been trying to arrest Bose for the past ten years. He tries to extract information from the four but in vain, they escape from there and decide to travel to Goa. Desperate for his promotion, Kabir is determined to capture the four. All four friends steal Boman's car which belongs to his father Nari (Asrani), who loves his car more than his son and threw his son out after he damaged his car. The friends manage to steal their car but not before hitting Nari on the head and making him unconscious. Unfortunately, Roy loses control of the car in a forest and hits it against a tree breaking both headlights. They decide to spend the night in the car. The next day Kabir is transferred to Yavatmal for failing to capture Bose. Furious he walks towards his table where Nari is waiting for him to file a complaint against his son for stealing his car. He gives Kabir the photos of Boman and his car. Meanwhile, all four come across a broken bridge which is the only way through the forest. They decide to jump the car but Boman is reluctant to do so. Unfortunately they manage to jump the car on the other side but it blasts off.

Kabir tracks the four down after discovering the destroyed car. He is able to learn the location of the treasure due to Manav's dumbness. He ties all four of them to a tree and sets off. However they manage to escape and it is revealed that Roy had actually cut the engine wires of Kabir's car so he must have not gone too far. They reach a dhabha and pretend to be detectives. They make the villagers believe that Kabir is a member of the Pasha gang and lures them to capture him for the reward would be Rs. 15 lakhs. Unfortunately Kabir defeats the villagers and he and the four arrive at a settlement - 60% would belong to the four and 40% would belong to Kabir. But Boman insists on having his money separately for damaging his car from the rest of the three. Consequently, a fight ensues and is decided that whoever reaches the treasure first would take all the money.

All four part ways and try to reach Goa as soon as possible. Roy encounters a dacoit Babubhai (Sanjay Mishra) and agree to divide the money among themselves provided they reach Goa as soon as possible. Boman also encounters his father. Though Nari initially wants to kill his son, changes his mind after he learns about the ten crores. Adi and Manav travel together. Kabir nearly escapes death as he hangs off a cliff and is rescued by some school children whose school bus he stole. All of them go through a series of humorous adventures before reaching Goa. Unfortunately all of them (except Kabir) reach the garden at the same time. Finally Roy explains that it is useless finding the treasure alone and all agree to find the money together. They all search for the big 'W'. Manav is able to locate the Palm trees which make the shape of a 'W' when a crow poos on Adi. But Kabir arrives there and tells them to divide the money against them to which all agree. They dig there and are able to find the money. But again a fight ensues over the payment for the damage of the car. All are enraged when Adi and Manav decide to pay the money as one unit but are separate units while taking money. The fight goes on during which Kabir takes all the money and runs. He tries to escape in a hot air balloon on a beach but finds it tied to a pole. He dives in an effort to cut the rope but is beaten up by the rest who pursue him. The balloon blows off shore and all are disheartened.

Conditions change when the wind changes direction and the balloon again blows onshore. They follow the balloon in a towing van. The balloon clashes against a pole and the bag falls down. All of them try to collect as much money as they can when suddenly some spot lights focus on them and a crowd cheers loudly behind them. They are actually standing in stage where a function is being held by an organisation named 'Help Orphans'. Seeing the money everybody thinks they have come here to donate money. All of them get emotional and all decide to donate the money for the orphans. The film ends on a happy note conveying that the fate of the money was already decided. It never belonged to the four friends. They were just a medium which helped the money reach its true destination.

• Sanjay Dutt as Inspector Kabir Nayak
• Riteish Deshmukh as Deshbandhu Roy
• Arshad Warsi as Aditya Shrivastav
• Aashish Chaudhary as Boman Contractor
• Javed Jaffrey as Manav Shrivastav
• Asrani as Nari Contractor
• Sanjay Mishra as Babubhai (Aatank)
• Vijay Raaz as Dev Kumar Malik
• Manoj Pahwa as The Pilot
• Tiku Talsania as Commissioner M I Chaturvedi
• Murli Sharma as Inspector Kulkarni
• Prem Chopra as Bose
• Suhasini Mulay as the Landlady
• Vijay Patkar as Air Traffic Controller
• Kiku Sharda as Constable
• Vinay Apte as Prabhakarn Shriperavardhana Attapatu Jaisurya Laxman Shivramkrishna Shivavenkata Rajashekhar Shrinivasan Trichapally Ikaparam Pila Perambdur Chinnaswami Muthuswami Vengopal Iyer
• Kurush Deboo as Dwivedi's son (Victim of Conmen's Fraud Painting)
• Ninad Kamat as Function Host
• Rana Jung Bahadur as Kailash (Dhaba Owner)
• Karmveer Choudhary in kailash da dhaba
• D. Santosh as Encounter COP
• Vaibhav Mathur as Dacoit's man
• Vishwajeet Soni as Bengali car guy
• Surendra Rajan

The film's soundtrack is composed by Adnan Sami with lyrics penned by Sameer. The songs, "Dekho Dekho" and "Miss India Marthi Mujhpe", were both known as the title song, since the main chorus of both the songs included the title "Dhamaal".

Track listing

All lyrics written by Sameer; all music composed by Adnan Sami.

A sequel named Double Dhamaal was released in 2011.