LOS ANGELES: Gearing up for its release, 'Oppenheimer' just dropped a five-minute opening look into Christopher Nolan's biopic, and it all plays out more like a horror movie than anything else.

The sneak peek starts off in black and white, showing a meeting called by US Atomic Energy Commission founder Lewis Strauss (Robert Downey Jr.) in which he and Oppenheimer talk about the Soviet Union testing an atomic bomb and its potential ramifications. Oppenheimer calls the building of the bomb, a race against Nazis.

The preview then enters a flashback in colour, going back to the time when Leslie Groves Jr. (Matt Damon) who was the director of Manhattan Project created the town of Los Alamos, for creation of the bomb.

Throughout the video, the entire team begins to crack under pressure including Oppenheimer himself, as they deal with the ticking clock as well as pondering over what this one project could to the future of humanity.

However, while still surrounded in doubt, Oppenheimer rallies everyone to complete the project, saying that there is no choice as this one bomb would be even more dangerous in the hands of the Nazis.

The video then cuts to the building of the bomb, and then the Trinity Test where they explode the very first atomic bomb showcasing the very aspects of nuclear fission, as well as the intricacies of the whole detonation without any CGI.

While a biopic, the realism of this small clip and the emotional weight behind it is enough to terrify most people, because the crux of the whole movie ultimately is what such a powerful weapon could do as insecurity and pressure take hold, but ultimately, all those involved in this historically monumental event are all compelled due to a lack of options.

Based on the Pulitzer Prize-winning book 'American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer' written by Kai Bird and the late Martin J Sherwin, 'Oppenheimer' packs a star-studded cast and will release theatrically on July 21.