Archie and Reggie are unhappy with Betty and Veronica's new muscle-bound interest, who just so happens to have recently edged Reggie off of the track team. So Reggie suggests that they use Dilton's new physique inhancing formula on themselves, which thus far has been proven to work on lizards. Dispite Archie's disapproval, both he and Reggie end up doused in the formula -- but instead of the desired result, they both turn invisible! While Dilton tries to correct the situation so that the boys don't vanish for good, Archie must track down Reggie, who is gleefully attempting to use his new-found invisibility to exact revenge on the girls' new crush.