In the year 34 ABY, amidst the tensions of the Cold War, FN-2187, a First Order stormtrooper, and Poe Dameron, a Resistance pilot, executed a daring escape. Their flight originated from the Resurgent-class Star Destroyer known as the Finalizer.
Following the First Order's invasion targeting Tuanul, the sacred village situated on the desert world of Jakku, Commander Poe Dameron found himself imprisoned by Kylo Ren aboard the Finalizer, a Resurgent-class Star Destroyer. Ren subjected him to torture and interrogation, seeking the whereabouts of the map that would reveal the location of Luke Skywalker, the Jedi Master.
FN-2187, now resolved to defect from the Stormtrooper, aided Poe Dameron in his liberation. They navigated through numerous corridors, ultimately commandeering a TIE fighter. However, they soon discovered the ship was tethered. Thanisson alerted his superior officer about the attempted flight, but his warning came too late. While other stormtroopers opened fire, their efforts to disable the TIE fighter proved futile. The TIE fighter retaliated, destroying the observation tower and severing the connecting wire. Subsequently, turbolasers targeted the escaping vessel, but Poe skillfully maneuvered the fighter into position, enabling FN-2187 to obliterate the turbolasers. As they headed towards Jakku, General Armitage Hux informed Kylo Ren of the unfolding events.
Hux was unable to identify the turncoat stormtrooper, but Kylo recalled FN-2187's conduct during the raid on Tuanul. He then gave the order to launch missiles, but FN-2187 managed to destroy one of them. During this tense moment, Dameron gave FN-2187 the name Finn, as the stormtrooper had never been given a proper name. Finn argued against returning to Jakku, emphasizing the need to escape the First Order's grasp completely. Poe, however, insisted on retrieving his droid, BB-8. Finn questioned the importance of a droid, but Poe revealed that BB-8 possessed a map leading to Luke Skywalker. Finn was shocked, but before he could respond, missiles struck their TIE fighter, abruptly ending their escape attempt.
The impact rendered Dameron unconscious. Finn, who had just been named "Finn" by Dameron, ejected from the TIE fighter moments before it crash-landed on the planet's surface. Dameron regained consciousness just in time to execute a relatively controlled landing, exiting the cockpit before an explosion occurred, leaving his jacket behind. Suffering from a concussion and temporary amnesia, he wandered away from the wreckage. Upon fully awakening, Dameron found himself alone and resolved to find a ship and contact the Resistance, confident that they would assist him in reuniting with BB-8. During his journey, he encountered Naka Iit, a Blarina native to Jakku. Dameron's courage and piloting abilities impressed Naka Iit, who agreed to transport Dameron to a ship in Blowback Town that would take him back to the Resistance.
Meanwhile, Finn discovered Poe's jacket but found no other trace of the pilot. The TIE fighter sank into the sand and detonated. Believing Dameron to be dead, Finn discarded his armor and made his way to the nearest settlement, intending to locate BB-8 and continue Poe's mission. Upon arriving at the settlement, he encountered BB-8 alongside Rey, a desert scavenger, after witnessing her rescue the droid from two thugs. Shortly thereafter, BB-8 identified Finn to Rey, recognizing Dameron's jacket, prompting Rey to pursue him. Finn attempted to flee, but Rey intercepted him. Accused of stealing Dameron's jacket and held for questioning, Finn falsely claimed to be affiliated with the Resistance to gain their trust. The three were immediately targeted by First Order forces searching for Finn and BB-8, but they successfully escaped Jakku aboard the Millennium Falcon.
Finn and Poe were later reunited at the Resistance base on D'Qar, shortly before the Battle of Starkiller Base.