• Composer : Shantanu Moitra
• Lyricist : Swanand Kirkire
• Singer : Shaan , Shreya Ghoshal

A humanoid alien lands on Earth naked on a research mission in Rajasthan but is stranded when the remote control for his spaceship is stolen. He manages to get the thief's cassette recorder. On the same day in Belgium, an Indian woman, Jaggu, meets a Pakistani, Sarfaraz, and falls in love with him. Jaggu's father objects to their relationship, citing their different religions. He consults godman Tapasvi Maharaj who predicts that Sarfaraz will betray Jaggu. Determined to prove them wrong, Jaggu asks Sarfaraz to marry her. At the wedding chapel, she is heartbroken when she receives an unsigned letter, believing it is from Sarfaraz, calling off the marriage due to cultural differences. Jaggu returns to India and becomes a news reporter. She meets the alien and is intrigued to see him distribute leaflets about the "missing" God. She earns his trust by rescuing him when he attempts to take money from a temple's collection box as a refund on God's broken promises. The alien tells her that he is an 'astronaut' from another planet. His people know nothing about dressing, religion, or verbal communication; they transfer ideas by holding hands. In a flashback, after being accidentally hit by a truck, the alien is befriended by bandmaster Bhairon Singh, who takes him along with his troop. Bhairon takes him to a brothel, where the alien holds a prostitute's hand for six hours and thus learns the Bhojpuri language. Bhairon tells him that his thief may be in Delhi. The alien leaves for Delhi. Due to his strange behaviour, people assume he is drunk and call him "peekay" or "PK" (Hindi for drunk); the alien adopts PK as a name (his people have no language and thus no names). People tell PK that only "God" can help him find his remote. He sincerely practices Indian religions, including Hinduism, Sikhism, Christianity and Islam, attempting to find "God", to no avail. He later discovers that Tapasvi has his remote, who claims it was a gift from God and refuses to return it. Jaggu promises PK that she will recover his remote and he can go back home. PK conjectures that Tapasvi and other godmen must be dialling a "wrong number" to communicate with God and are advising the public to engage in meaningless rituals. Jaggu encourages the public to expose fraudulent godmen, by sending their videos to her news channel. This "wrong number" campaign turns into a popular mass movement, to the dismay of Tapasvi. Meanwhile, Bhairon finds the thief and contacts PK, telling him that he sold his remote to Tapasvi. PK realises that Tapasvi was a fraud all along and that it was not a "wrong number". Bhairon brings the thief to Delhi, but both die in a terrorist attack. Tapasvi decides to confront PK on-air. Tapasvi asks PK what the "right number" is. PK says that "God that created us all" is the only concept people should believe in and that the other "duplicate Gods" are artificial. Tapasvi argues, saying that PK is trying to take people away from their Gods and that they will not stand for their Gods being taken away. He claims he has a direct connection to God and refers to his prediction of Sarfaraz's betrayal to try to prove that Muslims are liars. PK, having absorbed Jaggu's memories earlier, realises that Sarfaraz did not write the letter to Jaggu. Jaggu contacts the Pakistani Embassy where Sarfaraz worked part-time. The embassy tells her that Sarfaraz has been annoying them by repeatedly asking if they received a call from Delhi, implying that he still loves Jaggu. That day, Sarfaraz found the same letter and thought it was from Jaggu, and did not call her as he understood she was under family tension. Jaggu and Sarfaraz reconnect, and Tapasvi is forced by Jaggu's father to return PK's remote. Meanwhile, PK has fallen in love with Jaggu but refrains from telling her because she loves Sarfaraz. Having filled multiple audio tapes with her voice alone, he takes two suitcases full of tapes and extra batteries when leaving for home. He lies to Jaggu that the tapes contain a variety of Earthly noises which he will miss, such as crows and car horns. Jaggu realises his love for her by seeing the note he wrote for her earlier but does not directly confront him about it. PK does not even look back while going as he didn't want her to see his teary face which will giveaway that he loves her. After his departure, Jaggu publishes a book about him, with Sarfaraz and her family assisting. One year later, PK returns to Earth on a new research mission on human nature with more members of his species.

• Track 1 : Tharki Chokro ( थारकी चोकरो )
• Track 2 : Love Is a Waste of Time ( प्यार समय की बर्बादी है )
• Track 3 : Nanga Punga Dost ( नंगा पुंगा दोस्तो )
• Track 5 : Bhagwan Hai Kahan Re Tu ( भगवान है कहां रे तू )
• Track 6 : Dil Darbadar ( दिल दरबदरी )
• Track 7 : PK Dance Theme ( पीके डांस थीम )