The film stars Abhishek Bachchan as an NRI who arrives in India with his ailing grandmother (played by Waheeda Rehman) and begins discovering his roots before getting embroiled in a religious dispute involving a mysterious monkey-like attacker.

The film's soundtrack, composed by A. R. Rahman, was a commercial success and received positive reviews from music critics upon release.

The version submitted to the National Awards featured an alternate ending favored by Mehra, which was unavailable to the general public and shown only in a limited one-week theatrical release as well as the Venice Film Festival.

[6][7][8] Roshan accompanies his dying grandmother Annapurna to their ancestral property in Old Delhi where he is initially stunned by the mad rush of neighbours: Ali Baig the renaissance man, feuding brothers Madangopal and Jaigopal, their wives and families, Mamdu the confectioner, Gobar the simpleton, Sethji and many others.

Roshan accompanies his grandmother to the Ramleelas, hangs out at Mamdu's sweet stall, plays with the children, and gradually becomes steeped in the culture.

The lecherous old local money lender Lala Bhairam's wife Shashi is having an affair with a young photo-studio hand Suresh, a double timer also pursuing Madangopal's daughter Bittu who secretly prepares to audition for a popular reality show Indian Idol.

Roshan also comes to empathize with the caste-oppressed trash collector girl Jalebi, and crosses paths with the loutish inspector Ranvijay who blithely stretches his authorities to manhandle the locals.

On the other hand, the media is all abuzz with tales of a miscreant known as the "Kala Bandar" who attacks, steals and has caused the death of a few innocent people.

Later when Roshan confronts Bittu after Madangopal fixes her marriage forcibly, he is disappointed when she expresses her plan of eloping with Suresh in order to achieve her dreams, unaware of his hidden affair with Shashi and his other intentions.

In the meantime Gobar ventures into the sooni galli where Jalebi gives him a lock of her hair so he may return in triumph and bring peace to the community.

Roshan narrates that it is the Kala Bandar which is like the demon king Ravana, which can create hatred and divide among human beings.

Meeting his dead grandfather in a dream, Roshan searches for his phone, which in reality drops from his hand as the screen cuts black.

[16] Post the refusal from Asin Thottumkal, Sonam Kapoor was paired as the leading female character opposite Abhishek Bachchan.

[20] Production designer Samir Chanda, who had earlier worked with Mehra on Aks and Rang De Basanti, recreated inner lanes of Old Delhi at Sambhar, a town in Rajasthan with similar architecture.

Following the screening was an interactive question and answer round, consisting of the director with the rest of the star cast and a vast audience.

[23] The official trailer was released on 4 January 2009 which featured scenes from Delhi along with Jama Masjid, theatre groups, Red Fort at night, Sonam Kapoor coming out of a public escalator at Central Park in Delhi and finally Abhishek watching Sonam dancing with the pigeon "Masakali" on her head.

The film was supposed to be released on 13 February 2009 to avoid clash with Billu Barber, but A. R. Rahman's continued absence from the project led to a delayed-release.

[29] Rajeev Masand of CNN-IBN gave it 3 stars, saying that it's a story with heart and Delhi-6 isn't great cinema like Mehra's Rang De Basanti and has a frustrating climax.

[30] Rachel Saltz of The New York Times stated "Delhi-6 can be maddeningly vague, which robs its ending...of the impact it intends".

[37][38] Other videos released include the title track "Delhi-6", the romantic interlude "Rehna Tu" as well as the folky "Genda Phool," an adaptation of a folk song from Chhattisgarh.