An opening scene shows a famous ship, Lady in Blue, sinking into a storm, and a lone survivor, Captain Jagat Malhotra (Kabir Bedi) emerging on the sea shore.

Somewhere in the Bahamas, Aarav (Akshay Kumar) runs a successful fishing company under the title of Blue Fisheries. He shares a good bond with Sagar "Sethji" Singh (Sanjay Dutt) who works as a diver for Aarav's fishing company. Sagar is in a relationship with Mahima "Mona" Singhania (Lara Dutta) and plans to marry her.

Meanwhile, Sagar's younger brother Sameer "Sam" Singh (Zayed Khan) is based in Bangkok. Sam is a bike rider, and meets Nikita "Nikki" Malhotra (Katrina Kaif), a female biker who works for an underworld gangster named Gulshan Samnani (Rahul Dev). Sam is challenged by Gulshan to a bike race, and after Sam wins, he asks Nikki out for dinner. Before leaving, Gulshan asks Sam to work for him, but Sam refuses unless there's a large sum of money involved.

During Sam's date with Nikki, Nikki explains to Sam that the job Gulshan proposed would pay with $50,000. Gulshan hires Sam to work for him, but Sam is set up by Gulshan in failing to deliver a package costing Gulshan $50 million. Sam must either pay his money back or die. Sam does not have the money so he explains to Nikki, whom he now loves, that he is going on holiday to the Bahamas to visit his brother Sagar and doesn't think Gulshan will find him there. Sam arrives at Aarav's company and Sagar welcomes him happily. In the Bahamas, one ill-fated day, when sitting in a restaurant, Sam receives a call from Gulshan on Nikki's phone, explaining that he has killed Nikki, and knows where Sam is. At the same time, as he gets out of the restaurant, Sam is confronted by Gulshan and his crew, who surround Sam, and chase him on bikes. Aarav enters and brings everyone to a halt by shooting the bike wheels, saving Sam's life.

For now, Sam tells Aarav what he did wrong, and Aarav decides he needs to tell Sagar about the situation. When Sagar learns how much trouble Sam is in, Sam tries to convince Sagar to retrieve a famous treasure from Lady in Blue. Sagar refuses. The next day, Gulshan bombs Sagar's home, and kidnaps Mona, with a ransom of $50 million or Sam for her return. When Sagar tells Sam and Aarav, Sam decides that they need to go and rescue Mona as they already killed Nikki and will kill Mona too. But Aarav speaks up and says they don't know how far Gulshan is connected and they may all die, meaning the only option is to find the treasure, pay off Gulshan and use the rest of the money to live comfortably. Sagar is still hesitant and it is revealed that Sagar has a haunted and shocking past with Lady in Blue. Years ago, Sagar had to abandon his archaeologist father, Aadesh Singh, at the ship, to save his own life. However, after Aarav convinces Sagar that the treasure will save the lives of both Mona and Sam, Sagar finally agrees.

The three of them bring the treasure up and find Gulshan sitting on the top of his ship that he and his gang have steered up next to the ship belonging to Sam, Sagar, and Aarav. He tells Sam and Sagar that Aarav hired Gulshan to do all of this. Soon there is a fight between Sagar and Aarav, and Aarav jumps into the ocean after killing Gulshan. Mona, Sam, and Sagar are forced to leave him there, and Sagar agrees never to come back to the Lady in Blue, after losing two people who were close to him there - his father Aadesh and his friend Aarav.

Three months later Sagar gets a call from Aarav. Talking to them, Aarav reveals that he survived his leap into the ocean, and reveals to them that his grandfather was Captain Jagat Malhotra, the traitorous captain of the ship, Lady in Blue, who committed suicide after he was court-martialed. Aarav never admitted to Sagar who his grandfather was, because he didn't want to dishonor his family. Aarav explains that finding the treasure of the Lady in Blue would help bring honor back to his family name, and he befriended Sagar, knowing he was the only one who could take him to the treasure. Throughout the phone call, a woman's arm is seen around Aarav, and later, the woman asks to speak to Sam. It is revealed that the woman is Nikki, and she is Aarav's wife. She asks Sam to forgive her for deceiving him, but it isn't revealed if Sam said yes or no. However, while Sam answers there is a smile on Nikki's face. The film ends with Aarav and Nikki cuddling on one of Aarav's boats, and the end credits begin.

• Sanjay Dutt as Sagar "Sethji" Singh, Aarav's closest friend and employee
• Akshay Kumar as Aarav Malhotra, the owner of Blue Shipping and Fisheries
• Zayed Khan as Sameer "Sam" Singh, Sagar's brother and a biker racer
• Lara Dutta as Mahima "Mona" Singhania, a marine enthusiast and Sagar's love interest
• Rahul Dev as Gulshan Samnani, a gangster from Bangkok and Nikki's apparent brother, who is actually Aarav's pawn to bait Sagar into retrieving Lady in Blue
• Kabir Bedi in a special appearance as Jagat Sudhir Malhotra, the treacherous captain of the sunken ship Lady in Blue, and Aarav's grandfather
• Katrina Kaif in a special appearance as Nikita "Nikki" Malhotra, the biker chick and Aarav's wife
• Kylie Minogue in a guest appearance as herself in the song Chiggy Wiggy

The music of the film was composed by A. R. Rahman with lyrics provided by Abbas Tyrewala, Mayur Puri, Rajat Arora, Raqeeb Alam and Sukhwinder Singh. The music was promoted and digitally distributed by Hungama Digital Media Entertainment Pvt. Ltd.

The song Chiggy Wiggy was sung by pop singer Kylie Minogue and Sonu Nigam. Backing female vocals is given by Suzanne D'Mello and Phij Adams did the sound mixing for the song. Minogue also made a special appearance in the video of the song. The track "Aaj Dil Gustakh Hai", which begins with a sequence of Sukhwinder Singh's humming, followed by an acoustic guitar loop presents Shreya Ghoshal handling a westernised rendition. The backing vocalists for the song are Benny Dayal, Hentry Kuruvila, Shi Millhouse and Raven Millhouse. "Fiqrana" features vocals by Vijay Prakash and Shreya Ghoshal and was picturised as solo performances of Akshay Kumar, Lara Dutta and Zayed Khan. Sanjay Dutt, the actor playing the film's protagonist boycotted the promotional events since he was not included in this song, which remained chart topper for many weeks. "Bhoola Tujhe" is a romantic song sung by Rashid Ali. The Yeri voice for the song was by Kavita Belliga. The theme song for Blue was sung by Blaaze, with backing vocals by Raqeeb Alam, Sonu Kakkar, Jaspreet Jasz, Neha Kakkar and Dilshad Khan. "Rehnuma" was sung by Shreya Ghoshal and Sonu Nigam. "Yaar Mila Tha" was sung by Udit Narayan and Madhushree with backing vocals by Ujjayinee Roy, Shi Millhouse and Raven Millhouse. This track was not included in the film, but it is conceptualized as a song played out between the characters of Akshay and Katrina after the end of the film's plot when they talk about Zayed's character.

The official track listing:

Hindi (Blue)

Telugu (Blue)

All Lyrics were written by Rajashri.