Duncan is in the shack but he is unresponsive.
You tried to talk to him? That's bad. Some help wouldn't hurt.
Did you spot the telephone at the lower area?
If you use the telephone Cuddles will call to Tabby.
If you talk about Duncan to Tabby she will give you some hints.
Duncan likes milk and Cuddles will probably come up with a ploy for Duncan.
Go talk to Duncan, again. As you have talked with Tabby about Duncan, Cuddles will fool Duncan that there's a milk tycoon outside. Duncan will wake up, momentarily.
Maybe there should be a cat outside so that Duncan believes you.
Have you found a head, already? ?
There is a frozen head in the fridge.
Put it in display outside for Duncan to see. ?
Stick the mannequin head on a post.
Did you open the window, so that Duncan can see?
Move the mannequin head to the left post so that it is visible from the opened window. Duncan should now go out to talk to the head.