As the Sun becomes an expanding red giant and threatens to engulf the Earth in 100 years, the United Nations, now renamed as the United Earth Government (UEG), decides to proceed with the Moving Mountain Project, a proposal of building ten thousand gigantic nuclear fusion engines that can propel the Earth out of the Solar System towards another habitable star system. A sister project, the Lunar Exile Project, was also initiated that involves pushing the Moon away from the Earth, utilizing three such fusion engines to minimize its gravitational attraction on Earth. In doing so, the UEG shuts down and bans the Digital Life Project (DLP), which proposes the continuity of human civilization through digital immortality by developing mind uploading technologies. This ban occurs despite skepticism and increasingly violent protests from the public due to the increasing cost of the moving mountains project. Zhou Zhezhi (Li Xuejian) is the Chinese ambassador to the UEG. Hao Xiaoxi (Zhu Yanmanzi) is Zhou's personal assistant. Mike (Andy Friend) is the American ambassador to the UEG.The first phase of the Moving Mountain Project is to pilot two of such fusion engines, one as one of the 3 Lunar Exile engines built near a research base in the Moon's Campanus Crater, and the other located near the Space Elevator built in Libreville, Gabon. However, during the construction of the engines, a series of terrorist attacks by well-armed DLP supporters on the UEG facilities in 2044 resulted in a hacked drone attack on the space elevator (that connects to the ARK space station and then to the moon), as well as coordinated hacking of the elevator vehicles by highly trained infiltrators. Their aim was the destruction of the Ark Space Station supplying the lunar operation. Although UEG trainee astronaut Liu Peiqiang (Wu Jing) and his fellow trainees (Including Han Duoduo (Wang Zhi)) manage to defeat the hijackers on their vehicles, but this was after the hijackers detonated one elevator with a missile that bypassed the cargo bay using counterfeit passes that gave them access to the central intelligence center of the Ark Space Station. As a result, the top of the space elevator and the Ark Space station are critically damaged and crash down to Earth. As part of the defense, the Quantum computer 550C is activated to take over the automated defense capabilities of the Space Elevator and the Space Station. 550C stops the attacks by taking over all the drones and the stopping the remaining space elevators from crashing. 3521 people were killed in the attack and further 5137 injured.Due to this attack, many countries working on the pilot program pulled out, leaving China alone to take on finishing construction of the Lunar and Earth engine. People want to re-initiate the DLP and say that they don't want to pay for fixing a crisis 100 years into the future. Since activation, the 550C now monitors all communications on Earth. Meanwhile on the Moon, Tu Hengyu (Andy Lau), a computer engineer part of the Lunar Exile pilot program, is awakened from hibernation to receive a batch of supplies, which includes a 550C, the newest of the 550 Series quantum computer, intended for test running the Lunar engine. Using a 550A that appears to be owned by him, Tu Hengyu views a simulation of his daughter Tu Yaya, who had died in a car crash 5 years prior. As part of the DLP before it was outlawed, Tu Hengyu succeeded in recording his daughter's consciousness and storing it on a hard drive, with his mentor and project lead Ma Zhao (Ning Li) bearing the responsibility. However, Yaya's digital consciousness can only live for two minutes before restarting, due to the 550A's hardware restrictions. For this, Tu Hengyu sought to use the newer 550C, but was outright rejected by Ma Zhao. Ma says that the DLP was banned as it was felt that nobody would want to live in the physical world if it was possible to have a self-aware digital existence in these turbulent times. During transportation of the 550C, it was damaged by a sudden solar storm, and in a meeting with other accompanied scientists, Tu Hengyu proposed to use his 550A for the testing. In return, Tu asked Ma Zhao to involve him in future developments of the 550 series, in hopes of having a chance to give Yaya "a complete life".Following the successful test runs of both the Lunar engine, as well as the subsequent Earth engine, the UEG gives the full go ahead to the Moving Mountain Project. In the next 14 years, over 7000 engines were built at and north of the Equator, with those at the Equator being Torque engines that stop the Earth's rotation. Subterranean cities were built under every engine as well, providing shelter for ordinary citizens for the upcoming 2500-year interstellar journey, however a sorting plan made it that only 50% of the world's population can gain a spot in the underground cities. 550C is tasked with overseeing the entire project. Liu Peiqiang, in the meanwhile, marries colleague Han Duoduo (Wang Zhi) and subsequently conceives their son Liu Qi. The Moving Mountain Project is officially renamed as the Wandering Earth Project, and the Lunar Exile Project goes in full swing as the three completed lunar engines start to propel the Moon away from Earth. The Ark Space Station is rebuilt as a navigator station for the Wandering Earth Project.As time goes on, the Solar crisis becomes more and more imminent, evidenced by spikes in solar radiation. Due to the radiation, large parts of the world's population fell to cancer, Han Duoduo among one of them. More bad news struck as Liu Peiqiang was the only one in his family to obtain a spot in the subterranean cities, and only their son Liu Qi is not eligible to tag along. The Chinese Government is worried that intelligence agencies had knowledge of an impending attack in 2044, and now the next attack is predicated in 205807.In 2058, Liu Peiqiang applies for work in the rebuilt space station, now renamed the Navigator ISS, in hopes of being part of a preferential policy that could guarantee Liu Qi a spot and Han Duoduo could tag along as his guardian in the subterranean cities as well. During an interview conducted by an offline AI-equipped 550W, the newest and most advanced 550 series iteration, Liu Peiqiang becomes enraged by the 550W as it confirms his family-oriented intentions of working aboard the Navigator ISS, all being part of a stress test personalized for each candidate. 550W tells Liu that his best option is to hand over custody of his son to his uncle, as his wife would be dead in 84 days.Tu Hengyu, being one of the examiners, witnesses Liu Peiqiang's anger unfold, and has a flashback of the car crash that killed his daughter. Having not seen his daughter in the past 14 years, and having been influenced by Liu Peiqiang's outburst, the now elderly Tu Hengyu decides to upload Tu Yaya's recorded consciousness into the 550W supercomputer still kept in the interview room. Immediately after doing this upload, the lunar engines overload and then explode, sending the Moon on a collision course towards Earth. Tu Hengyu, having broken the law by the upload, was immediately arrested and imprisoned.To deal with the "Lunar Fall crisis", the UEG initiates a backup plan that involves detonating all of the Earth's nuclear weapons on a concentrated phased array on the Campanus Crater on the moon, triggering nuclear fusion within the Moon's core, thereby leading to its implosion. After that, the 7000 Earth Engines will be powered up to propel the Earth out of the Lunar debris' way. Earth will have 30 minutes to escape the lunar implosion and the accompanying debris, once the nuclear bombs are detonated. However, as the Lunar Fall crisis happened on such a short order, the dedicated control network of the Earth Engines haven't been completed. Thereby, via rebooting the Internet root server data centers located in Tokyo, Beijing and Dulles, a plan was initiated to restart the internet, which had been long shut down, to use as a control network. Tu Hengyu, while serving his jail term, was recalled by the Chinese government to undertake the task of restarting Beijing's root server as part of a team which included his mentor Ma Zhao.The counter for the Lunar Fall crisis faces numerous setbacks due to the difficulties in nuclear code decryption, further exacerbated by the short time window before the moon reaches its Roche limit and fragments into pieces which will destroy the Earth. Liu Peiqiang, as part of the mission detail to place nukes on the Moon, narrowly avoids death as his team's spaceship crashes into debris sent up by the exploded Lunar engines. He finds transport in the abandoned research base, as well as a lander that he used to send the rest of his team back to the Navigator ISS with, much to their displeasure, while he himself transports the nukes assigned to his team.In the meantime, the code deciphering hits a deadlock, which led to 300 astronauts over the age of 50 voluntarily sacrificing themselves in order to manually detonate the nukes. Liu narrowly survives the nuclear detonation, managing to pilot an abandoned Russian transport capsule back to the Navigator ISS. Around this time, lunar debris had already started hitting the Earth, one of which scored a direct hit on Beijing's data center, flooding the insides and drowning Ma Zhao. Tu Hengyu, realizing he doesn't have long before drowning as well, uploads a copy of his own recorded consciousness into the network. Initially believing to have failed, the UEG broadcasts a final message to humanity, warning that the Moon will crash into Earth in 3 days. This leads to mass panic, looting, and riots around the world. Reuniting with Tu Yaya, Tu Hengyu's digital self manages to reboot the last Internet server in time, activating the Earth engines together and moving the Earth away from the course of the lunar debris. The Wandering Earth Project then officially sets sail with the Earth's course towards Jupiter.In 2065, the Earth is accelerating around the Sun, and is projected to pass Jupiter in 2075. The next attack is predicted in 2075. The remaining 3000 engines and all 10,000 underground cities are completed. With the slingshots around sun and Jupiter, Earth will accelerated to 0.5% the speed of light, spend 1500 years cruising and then decelerating for the next 700 years. In 2500 years, Earth will reach Alpha Centauri, becoming a new member of the star system.In a mid-credits scene, Tu's digital self is addressed by the 550W artificial intelligence, who now goes by the personified name "MOSS" ("550W" upside down). The now-sentient supercomputer reveals that it has been behind every crisis that has ever harmed humanity's efforts to save themselves, adding that it will also trigger many more in the future.