House of Horrors

You pretend you hear someone knocking at the door, and say to Hiccup, "did you hear that? I think someone is at the entrance. You should go check it out."

Hiccup nods and leaves the living room, leaving you free to look around.

You move over to the couch and realise it's a sofa-bed, so you pull up on the cushion and find a note hidden underneath!

It simply says "no-one will live".

What do you do now?