Macross Delta is set in the year 2067, 8 years after the events of Macross Frontier in a remote part of the Milky Way Galaxy called the Brisingr Globular Cluster, which is plagued by the Var Syndrome, a mysterious phenomenon which turns people berserk without any apparent cause. A team of talented idols, the Walküre, uses the power of their songs to calm down the infected by the Var Syndrome, assisted by the Delta Flight, a team of experienced Valkyrie pilots, while facing the interference from the Aerial Knights of the Windermere Kingdom, which found a way to exploit the infection on their favor as part of their plan to resume war against the New United Government for control of the Cluster.