Lakhan Singh (Sonu Sood), a.k.a. Lucky, is the "kinng of the Australian underworld." He is accompanied by his Sikh mafia associates, Julie (Neha Dhupia), Mika (Jaaved Jaffrey), Pankaj Udaas (Yashpal Sharma), Raftaar (Sudhanshu Pandey), Dilbaugh Singh (Manoj Pahwa) and Guruji Gurbaksh Singh (Kamal Chopra). In a small village in Punjab, the birthplace of Lucky, there lives another Sikh, Happy Singh (Akshay Kumar). Happy, though good at heart, has unintentionally caused many problems in the village, and the villagers are fed up with him. They decide to send Happy on a long trip to Australia with his friend Rangeela (Om Puri) to bring Lucky back to Punjab, which will keep Happy out of the village for some time and bring peace to the village.
But at the airport, Happy's and Rangeela's tickets to Australia are accidentally exchanged with those of Puneet (Ranvir Shorey), who was to fly to Egypt. In Egypt, Happy meets Sonia (Katrina Kaif) and falls deeply in love with her. But he does not express his love to her. Leaving her behind, he heads to Australia to meet Lucky. Lucky refuses to return to his hometown and throws Happy and Rangeela out of his house. Penniless, Happy finds warmth and affection in an elderly lady (Kirron Kher) who provides him with food in spite of being a stranger.
Lucky winds up in hospital, paralyzed, after a series of violent incidents that Happy has caused. (In one of these incidents, his head is bumped severely, and the trauma from the resultant concussion is what paralyzes him.) Unexpectedly, it is Happy who is given the position of the "Kinng." The lady who helped Happy is obviously worried and depressed, as her daughter is returning from Egypt with her wealthy boyfriend, Puneet. The daughter does not know that after the death of her father years ago, her mother had become poverty-stricken and been reduced to work as a flower seller. Happy gives her Lucky's spacious house and makes all his mafia associates work for her.
The lady's daughter arrives; to Happy's horror, she is none other than Sonia. Heartbroken, Happy is forced to make a show of happiness to Sonia. Puneet says that he too would have had a good time with Happy and Sonia in Egypt had his ticket to Egypt not been exchanged in the airport, because of which he had ended up in Australia. Puneet had always been jealous of Sonia being with Happy; however, he doubts something is going on between them.
Meanwhile, Lucky's gang members spend enough time with the kindhearted Kinng for most of them to be reformed and give up lawless lives in favour of law-abiding ones.
In spite of herself, Sonia falls in love with Happy and the truth becomes difficult to hide. Puneet sets his heart to marry Sonia. Sonia gets trapped in an emotional tug-of-war between Puneet, who loves her, and Happy, whom she loves.
In the confusion, Happy's associates reveal to Puneet who they are, and that Happy is the Kinng of the Australian underworld, not a manager as Puneet had believed him to be. Puneet, in turn, reveals this to Sonia, who has become aware of her own poverty.
Soon Puneet meets Mika, Lucky's other brother, who agrees to kill Happy. Puneet's motives to kill Happy, however, differ from Mika's: Puneet wants to kill Happy to keep Sonia away from him, whereas Mika wants to kill Happy to make himself Kinng.
On the dawn of the wedding day, the sound of gunshots firing can be heard. Happy takes Sonia in order to save her--and unknowingly, both run around the fire seven times, essentially getting married. (During all this, Lucky's head is bumped, and the trauma-induced paralysis he had suffered from is relieved.) Suddenly, Mika turns up on the spot, ready to kill Happy, armed with a gang and his new special glasses and hearing aid. As he is about to shoot, Lucky steps up and stops him. Then a dialogue ensues between Mika, Happy, Lucky, and the associates of the Kinng. Then Happy tells him that being the "kinng" is not as great as it may seem and explains him the characteristics of a true Sikh. Lucky confesses that he had always found being Kinng a source of misery, because a true kinng fights for others, not for himself. Overcome with remorse, Mika drops his gun. The movie ends with Happy's and Sonia's marriage and the returns of Lucky and his gang members to their homes in the village.
The music of the film was composed by Pritam and the lyrics were written by Mayur Puri. The title song was composed by the British bhangra band RDB. The soundtrack was launched officially at the IIFA Awards in Bangkok on 8 June 2008.
Snoop Dogg also has a cameo in the video of the title song.
Shreya Ghoshal, who sang the song "Teri Ore," won the Filmfare Award for Best Female Playback Singer and the IIFA Award for Best Female Playback. Mayur Puri was nominated for the Star Screen Awards, in the "Best Lyrics" category, for the same song. According to the Indian trade website Box Office India, with around 18,00,000 units sold, this film's soundtrack album was the year's third highest-selling.
The soundtrack of the film is as follows:
Some members of the Sikh community had expressed their displeasure over the portrayal of Sikhs in the movie. On 1 August 2008, the Delhi Sikh Gurdwara Management Committee (DSGMC) wrote a letter to Sheila Dikshit, the chief minister of Delhi, asking her to ban the movie, as the trailer showed Akshay Kumar's character sporting a trimmed beard. But according to their religious guidelines, male Sikhs should not trim their beards, and the DSGMC found this offensive. After negotiations with the DSGMC authorities, the film was given clearance on 7 August 2008.