Two American F-35 Lightning II fighters enter Chinese airspace and cause havoc near the coast. Flying at supersonic speeds, the F-35s create sonic booms that damage an oil refinery and affect local fishing boats. Chinese pilot Lei Yu (Yibo Wang) intercepts the F-35s with his Chengdu J-10. Lei Yu pushes the limits of his craft to compete against the 5th generation fighters; the intruding aircraft then leave the airspace. Lei Yu's craft suffers engine problems including a flame out during a vertical climb, which force him to make an emergency landing.In a meeting, Lei Yu's superiors are critical of him pushing the jet that far, but Lei Yu argues it was the only way to fight against a superior enemy. The higher-ups discuss the main issue: foreign 5th generation fighters have a huge advantage over their 4th generation fighters. The Chinese Jet engines are not yet capable to compete with foreign enemy aircraft. Secretly, the Chinese have been developing the 5th generation Chengdu J-20 in order to counter foreign 5th generation threats. Commander Zhang Ting (Jun Hu) invites Lei Yu to join him in the new stealth fighter program and he agrees. The other test pilots include Deng Fang, Gao Yingjun (Yu Bu), Xia Pengfei (Yujia Zhai), Li Xiaohang (Xin Lu), Tong Gan (Zichen Wang) among others. Shen Tianran (Dongyu Zhou) is the evaluating officer of physical fitness tests of all pilots.At the training facility, Lei Yu and his squad endure rigorous training by pushing their physical and mental limits. The J-20 is still going through refinement as the prototype WS-13 Taishan engine is incomplete. They've been using alternative jets to test the engine's capabilities before installing it in the J-20.During a flight test with Commander Ting, Lei Yu and Ting lose thrust and enter into a spiral dive. Lei Yu believes the situation is dangerous and ejects, while Ting manages to regain control of the aircraft and land the plane. Due to the ejection, the test data from the flight is lost due to instrument failure. So, Lei risked their lives for basically nothing. The incident gets Lei Yu grounded, and he is expected to leave the training facility. During his grounding, he studies the mechanical flaws and proposes an anti-stall parachute. This parachute will allow the safety of test pilots and aircraft while allowing pilots to collect the crucial limits data without failure.Ting decides to have Lei Yu fly with him on his last day to test the fighter's engine and missiles, when the fighter suffers dual engine failure. The test was to ingest the missile smoke into the engines to see if the engine still performs. But both engines catch fire due to overheating. Ting and Lei Yu agree to eject together, but Ting stays in the aircraft and steers the jet outside of the city in order to prevent civilian casualties, dying in the process. Ting is later given a military burial, while Lei Yu chooses to stay with the squad to complete the J-20. Since Zhang is dead, Deng Fang is appointed the new chief pilot of the unit. Lei Yu refuses to go back home with his parents, even after his father admonishes him that China cannot compete with foreign powers to develop a stealth fighter all by itself. Lei Yu is determined to contribute to China's success.Lei Yu then designs a fighter anti-stall parachute deployment system and tests it extensively in the ground. After extensive testing and modifications, the parachute deployment system works. Meanwhile, the design and engineering team makes changes to the engine so that it can operate with the hot gases from the missile exhaust, without overheating and rupturing.Lei Yu and the chief pilot, Deng Fang (Yosh Yu), test the newest engine after Ting's death. They successfully fire 3 missiles and ingest the smoke into the engines, and it works. While testing the jet's ability to get out of a spiraling dive, a flock of birds strikes the cockpit, knocking out both crew members. Lei Yu manages to recover and attempt to regain control. The fighter has his anti-stall parachute installed and uses it to get the J-11 out of the spin, but the chute can't be ejected. Lei Yu receives orders to eject the aircraft, which would mean abandoning Deng Fang to his death, since he is still unconscious. Lei Yu pushes the engine to rip out the chute and tries to regain control as the blood in his eyes blinds him. He manages to pull up and prove the new improvements worked; this marks the completion of their prototype and onto mass production.In a later encounter, American stealth fighters and drones infiltrate Chinese air space again. Lei Yu and Deng Fang launch in their completed J-20s and shoot down the drones. They then proceed to engage the F-35s. Since shooting down the American fighters would lead to an international incident, Lei Yu warns the pilots and the F-35s retreat from the airspace. In a mid-credits scene, Lei Yu and his squadron perform a surprise flyby by deploying colored smoke above a soccer field to show respect to Commander Ting's son.