Phineas and Ferb: Oh, There You Are, Perry/Swiss Family Phineas

When Phineas and Ferb think Perry is lost, they build a musical device to find him. Meanwhile, Candace, who fears she is at fault for Perry's disappearance, combs the Tri-State area to find him. As it turns out, Doofenshmirtz has been downgraded to a low-level threat and Perry has been reassigned to a more dangerous villain, and possibly, a new family./ The family becomes marooned after a summer storm shipwrecks them on an island, and Phineas, Ferb and Isabella use the opportunity to build a Swiss Family style tree house. Meanwhile, Candace tries to get them to build a boat so she can get back in time for Jeremy's party. Dr. Doofenshmirtz is also on the island, using the free monkey labor to boost a new business.