Fionna and Cake – with the help of the former Ice King, Simon Petrikov - embark on a multiverse-hopping adventure and journey of self-discovery. All the while a powerful new antagonist determined to track them down and erase them from existence, lurks in the shadows.

Phineas and Ferb travel across the galaxy to rescue their older sister Candace, who has been abducted by aliens and taken to a utopia in a far-off planet, free of her pesky little brothers.