Rowlf hadn't disapeared - he'd just watched a scary movie the night before and had gone to see Nanny. The secret passage was actually an old dumbwaiter which Animal found and had been using to move between the attic, kichen and basement.
Keywords: childhood , adventure , babies , fantasy , fantasy-adventure , imagination , imaginative , kindergarten , muppets , musical-tvshow , nanny , slice-of-life