"Bang Bang!" is a Bollywood action thriller film released in 2014. It is a remake of the Hollywood film "Knight and Day" and features Hrithik Roshan and Katrina Kaif in the lead roles. Here's a brief summary of the movie:

The story revolves around Rajveer Nanda (played by Hrithik Roshan), a charming and enigmatic man with exceptional combat skills and a mysterious past. He crosses paths with Harleen Sahni (played by Katrina Kaif), an ordinary bank receptionist who is on her way to a dream vacation in Europe.

Rajveer's life takes a turn when he becomes involved in a secret mission that puts him on the run from both the Indian intelligence agencies and international assassins. Harleen unwittingly gets entangled in this high-stakes adventure when she crosses paths with Rajveer at a dance competition.

As they embark on a whirlwind journey across Europe, dodging bullets, explosions, and car chases, Harleen becomes increasingly aware of Rajveer's true identity and the dangerous world he inhabits. Despite the constant danger, a romantic bond begins to develop between them.

The movie is filled with breathtaking action sequences, exotic locations, and a blend of humor and romance. It explores themes of love, trust, and the sacrifices made for the greater good. As the story unfolds, Rajveer and Harleen must outsmart their pursuers and uncover the truth behind the mission.

"Bang Bang!" is known for its high-octane action scenes, impressive stunts, and the charismatic performances of Hrithik Roshan and Katrina Kaif. It's a thrilling and entertaining film that combines elements of romance and espionage in a visually stunning package.