Captain America Steve Rogers (Chris Evans) leads the newly formed Avengers to continue to maintain world peace. However, during a mission, members of the alliance accidentally caused a large number of civilian casualties, which aroused political pressure. The government decided to manage and lead the Avengers through a regulatory system. The alliance was therefore divided into two factions: one side was led by Steve Rogers, who advocated maintaining the freedom of members and protecting the world without government interference; the other side followed Tony Stark (Robert Downey Jr.), who unexpectedly decided to support the government's regulatory and accountability system. The mysterious Bucky (Sebastian Stan) seems to have become a key figure in the civil war...