Jim Austin, more affectionately known as Lunk, is a biomaintenance engineer that returned from the expeditionary forces who returned to fight off the Robotech Masters. While supporting a ground unit, he arrives in time to see his best friend the only survivor of the unit and being hotly pursued by Invid. Jim loses his nerve and flees the scene leaving his friend to certain death. Jim is ashamed of his desertion and hides his past and assumes the nickname of Lunk.
When a local gang of bikers find out about his past, they begin terrorizing him and his friends. One day, while chasing Lunk and a friend, they cause him to crash. Lunk escapes, but his friend is not so lucky. While Lunk is about to run away again, Scott and Rook are ready and willing to go after the gang and rescue his friend. This reawakens Lunk's sense of duty, and he leads Scott to an old Alpha fighter he'd been maintaining for years, just in case.... Lunk attempts to complete his best friend from the war's last request and return a book to his father. When they reach the village where his friend's father lived, they find that the locals killed him when he tried to teach them that they couldn't fight the invid. Lunk slowly regains his self-esteem while he helps the group out and maintains their fighting mecha.