A colossal space monster emerged in a city and started to wreck it. People fled with screams. Among them were five high school students: En, Kai, Shin, Yoku, and Ryu. However, they failed to escape and rushed into a nearby parked patrol car. The monster was approaching them. As they began to accept their death, the patrol car glowed blue-white and vanished into a mysterious space, taking them with it. While they were astonished, an alien appeared before them. He was a Bravian, an officer of the Space Police Organization responsible for maintaining peace and order in the universe. He explained to them that he had been targeted by ferocious aliens in the Space Prison Sargasso. He added that he had given them a battle machine, "Dag Beagle," created by copying machines on Earth, in order to fight against Sargasso. They transformed into Dagwon using Bravian's power and fought against space monsters. At that moment, the patrol car appeared in front of En. En merged with the car and transformed into the Brave Robot Dag Fire, then defeated the enemy. However, the battle between the Brave Dagwon and the felonious aliens of Sargasso had only just begun.