The story is adapted from the game of the same name by Microsoft. In 2552 AD, because the population of the earth was too large, humans had to start migrating to many planets in the interstellar space to develop new space. After a space immigration organization suddenly disappeared, only one battleship of the fleet sent to investigate the matter returned to the base. Since then, the invasion of humans by the alien race Covenant has begun. The technology of the Covenant is far superior to that of the earth, forcing the earth's army to retreat step by step. Finally, humans have to prepare to go to the distant and unexplored universe to seek a ray of life. During the exploration process, the commander and his team were discovered and caught up by the Covenant fleet. At the critical moment, they discovered Halo, a huge alien ring-shaped world with a diameter of 10,000 kilometers and breathable gas. In this huge living ring, there are incredible creatures, strange plants, twisted underground nests, huge mountains, and countless angry aliens. After the spacecraft was destroyed, some human members landed on the surface of Halo and started a war with the Covenant...