The life of an unsuccessful writer is transformed by a top-secret 'smart drug' that allows him to use 100% of his brain and become a perfect version of himself. His enhanced abilities soon attract shadowy forces that threaten his new life.

Yet to fulfill their rock and roll destiny, the stakes are higher than ever for the now middle-aged Bill and Ted who set out on a new adventure when a visitor from the future warns them that only their song can save life as we know it.