In the 23rd century, the Federation starship USS Kelvin is investigating a “lightning storm” in space. A Romulan ship, Narada, emerges from the storm and attacks Kelvin. Narada’s first officer, Ayel, demands that Kelvin’s Captain Robau come aboard to negotiate a truce. Robau is questioned about the current stardate and an “Ambassador Spock”, whom he does not recognize. Narada’s commander, Nero, kills him, and resumes attacking Kelvin. George Kirk, Kelvin’s first officer, orders the ship’s personnel, including his pregnant wife Winona, to abandon ship while he pilots Kelvin on a collision course with Narada. Kirk sacrifices his life to ensure Winona’s survival as she gives birth to James T. Kirk.
Seventeen years later on the planet Vulcan, a young Spock is accepted to join the Vulcan Science Academy. Realizing that the Academy views his human mother Amanda as a “disadvantage”, he joins Starfleet instead. On Earth, Kirk becomes a reckless but intelligent young adult. Following a bar fight with Starfleet cadets accompanying Nyota Uhura, Kirk meets Captain Christopher Pike, who encourages him to enlist in Starfleet Academy, where Kirk meets and befriends doctor Leonard McCoy.
Three years later, Commander Spock accuses Kirk of cheating during the Kobayashi Maru simulation. Kirk argues that cheating was acceptable because the simulation was designed to be unbeatable. The disciplinary hearing is interrupted by a distress signal from Vulcan. With the primary fleet out of range, the cadets are mobilized. McCoy and Kirk board Pike’s ship, the Enterprise. Realizing that the “lightning storm” observed near Vulcan is similar to the one that occurred when he was born, Kirk breaks protocol to convince Pike that the distress signal is a trap.