When does Adventure Time: Fionna and Cake return?

The series follows the eponymous Fionna and Cake the Cat, alternate-universe versions of Finn the Human and Jake the Dog. It is a spin-off of the Cartoon Network series Adventure Time (2010–2018) and the third main installment in the Adventure Time franchise. The series also features Simon Petrikov, a character who for most of Adventure Time had been known as the Ice King.