In the early 1960s, during the height of the Cold War, the Soviet Union embarks on a mission to send the first man into open space, aiming to outpace the United States in the space race. Cosmonaut Pavel Belyayev and his rookie partner Alexei Leonov are selected for the mission, undergoing intense training and facing numerous challenges to prove their readiness. As the launch approaches, they are confronted with technical issues and personal dilemmas that test their resolve and dedication. Through resilience and camaraderie, Belyayev and Leonov prepare to make history while grappling with the immense pressures of their pioneering endeavor.

On launch day, the two cosmonauts lift off into orbit aboard the Voskhod 2 spacecraft. Once in space, they face a series of unexpected obstacles that put their mission in jeopardy. The mission reaches a critical point as Leonov attempts to step out of the spacecraft for the first-ever spacewalk. Complications arise that push their skills and nerves to the limit. The astronauts must rely on their training, ingenuity, and each other to overcome the harrowing situation and complete their groundbreaking mission.