In the year 2099, Alchemax scientist Walker Sloan seeks to gain power and fortune by traveling back in time to the present day in order to use his knowledge of future technology to found Alchemax much earlier in time. This causes the future of 2099 to change to a dystopia where Alchemax rules the world with an iron fist. Spider-Man & Spider-Man 2099 is aware of the plan and finds out that Sloan's actions are not only responsible for the changes in the timeline but will also cause the death of Phineas Flynn & Isabella Garcia Shapiro at the hands of a brainwashed Anti-Venom. Miguel & Peter warns Phineas, Ferb & the gang of the impending danger, and they must work together across time to save the future and Phineas & Isabella's life.