The Guardians received a message from Chess saying that Flaming Star had run into trouble in Colorado. Exact coordinates and a contact followed. The Guardians left immediately, little realizing the horrible music to come.
The Guardians met their contact David Lens, who in reality was the amazing hero Shadow Knight, scourge of the boardrooms, and learned about the A Capellan Harmony. After coordinating their efforts with local freedom fighters, the heroes attempted to free Flaming Star. While attacking the scout stage, the Guardians were opposed by the BOSS, a Star. After listening to a rendition of 'Born in the A.C.H', the Guardians decided to kill all the aliens. The battle with the defending choir was fierce, as they sang loudly. As the Guardians drove them back, they switched from A Capella to instruments that paralyzed, but still they lost.
The Guardians freed Flaming Star, but she seemed dazed and deaf after her ordeal. The Guardians decided to fly the scout stage to Chess headquarters to tell them about this horrible threat. The flyers chosen were the dynamic duet, QUIASAR and ENTROPY. The two heroes took a prisoner and several bodies as proof of the invading A Capellan tour. Unfortunately, the duet found that the A Capellans had surrounded the town with a gigantic fortissimo. Triggering the stage's laser show, however, allowed them to escape.
The duet returned with a tuba borrowed from the military. The Guardians then struck at the fortissimo stations, capturing many singers. With the fortissimo weakened, the Guardians returned to Chess to plan a benefit attack. During the planning, they were amazingly joined by evil clones of Crocodile, Spectre, and Zap, who promised their musical support.
Intelligence had pinpointed the construction of a giant sound stage that powered a fortissimo. The Guardians attacked the headquarters of the A Capellans, which housed Agent Rall and the Lady Trio. Meanwhile, Justice Force would wait until the Laser show was over, and assault the sound stage. Unfortunately, Justice Force left too soon and got caught up in the laser show, but the final victory still went to the Guardians. The A Capellans canceled their show and went home.