The film opens with the Federation starship USS Kelvin investigating a “lightning storm” in space. It turns out to be a black hole, and the Narada, a Romulan mining vessel, emerges from it and attacks. The Kelvin‘s captain, Richard Robau (Faran Tahir) is captured and killed by the Romulan captain Nero (Eric Bana). First officer George Kirk (Chris Hemsworth) takes command and sacrifices himself and the Kelvin by ramming it into the Romulan ship in order to allow the rest of the crew to escape. During the escape, George’s wife Winona (Jennifer Morrison) gives birth to a son: James Tiberius Kirk.
About 22 years later, Kirk (Chris Pine) grows into an intelligent but reckless young man. He meets Uhura (Zoe Saldana) and Captain Christopher Pike (Bruce Greenwood) in a bar in Iowa, where Pike convices Kirk to enlist in Starfleet Academy and follow in his father’s footsteps. During his eventful education on Earth, he is suspended for cheating on the Kobayashi Maru designed by the half-Vulcan, half-human Spock (Zachary Quinto). Despite this, Kirk is smuggled onboard the USS Enterprise by his friend, Dr. Leonard “Bones” McCoy (Karl Urban), as it is sent on its first mission to investigate a distress signal originating from the planet Vulcan; Captain Pike commands the ship, with Spock as his first officer, and Uhura is also assigned to the ship. En-route, Kirk realizes that the situation is similar to the one 25 years ago when his father died and, with the help of Uhura and McCoy, manages to convince Pike and Spock that the Enterprise is heading into a trap. When the Enterprise arrives, they find the rest of the Starfleet ships destroyed and Nero’s ship, the Narada, using a drilling apparatus to tunnel to the planet’s core. After promoting Spock to captain and Kirk to first officer, Pike surrenders to Nero, giving Kirk and Hikaru Sulu (John Cho) a chance to destroy the drill. Nevertheless, Nero destroys Vulcan with a small amount of “red matter”, dropped into the planet’s core, which creates a black hole that consumes the planet from within. Six billion of the Vulcan people die, including Spock’s human mother, Amanda (Winona Ryder).
Nero puts the Narada on a course for Earth with the intention of destroying it. Kirk wants to follow Nero immediately, but Spock insists that the Enterprise should regroup with the fleet as per their orders. Spock has Kirk forcibly removed from the Enterprise and stranded on the nearby ice planet Delta Vega, only for him to be rescued by an aging Vulcan who reveals himself to be Ambassador Spock (Leonard Nimoy). This elderly Spock explains that, 120 years in the future, he tried to save the Romulan homeworld “Romulus” from being destroyed by a nearby supernova, using the red matter in his ship to create a black hole that would neutralise the threat. Though Spock did not complete his mission in time to save Romulus—resulting in Nero’s vow to take revenge on Spock and the Federation—he stopped the supernova, and the resulting black hole transported Spock’s ship and the Narada into the past. Spock takes Kirk to a nearby Starfleet outpost and introduces him to Montgomery Scott (Simon Pegg), a master engineer and pioneer of transporter technology. Scott and Kirk are transported back to the Enterprise and, taking Ambassador Spock’s advice, Kirk goads the younger Spock into attacking him and demonstrating that he is “emotionally compromised”. As a result, Spock relieves himself of command; because Kirk is the next-highest ranking officer, he becomes the new captain of the Enterprise.
Captain Kirk takes the Enterprise to Earth, intending to stop the Narada on his own. Spock, Scott and math-whiz Pavel Chekov (Anton Yelchin) figure out a way to lie in wait for the Narada and beam aboard, allowing Kirk and Spock to stage a surprise attack. While Spock steals Ambassador Spock’s captured ship and lures the Narada away from Earth, Kirk rescues Pike. With the assistance of the Enterprise, Spock then rams Ambassador Spock’s ship into the Narada, detonating the red matter and creating a black hole that, aided by a full barrage of the Enterprise‘s weaponry, destroys the Narada completely. Kirk, Spock and Pike are rescued by the Enterprise via transporter, which is in turn saved from being pulled into the black hole by Scott. Back on Earth, Kirk is commended, promoted to captain and given permanent command of the Enterprise from Pike, now a Fleet Admiral and confined to a wheelchair. Ambassador Spock visits his younger self and explains that he helped Kirk directly because he wanted to ensure that the young Spock and Kirk would come to an understanding of each other and become friends.