It is almost the end of UC 0079. Having pushed Principality of Zeon forces off of Earth, the Earth Federation plans for Operation Star One. In preparation for the operation, the Thoroughbred is sent to disrupt the Zeon supply line between Solomon and Granada. To do this, it is given two experimental Gundams, Unit 4 and Unit 5.

The mission is simple. Hold out against Zeon forces while making sure the supply line is unusable. Gundam's Unit 4 & 5's goal is to use their heavy weaponry together in order to wipeout the fleets before they can send a message for help. Only issue is that the Mega Beam Launcher of the Unit 4 refuses to properly work with it's supply pack.

(Based on the Gundam Side Story "Space, at the End of a Flash".)