We have a log burner in an old fireplace, with a plate of metal above it up the chimney, with a hole for the log burner floo. I thought the top of the original chimney/floo thing would be blocked off but I can hear something scratching around just the other side of the metal. Everything appears to be sealed.
After my initial thoughts of someone bursting out horror-movie-style and killing us, I'm now really worried about whatever creature is stuck there! WWYD?