couple of things, Dhuran. I think your set-up still needs to be a little clearer; start off with an establishing shot of the country house/mansion, then another shot of the interior (perhaps the grand hallway) and then another shot of the entrance to the museum room (otherwise your audience doesn't really know where the action is happening). Also, I think you need to consider telling the audience what Mercer looks like BEFORE he appears in the story (otherwise his entrance is a bit 'who is he?'). Why not consider in the establishing shots have a panning shot that shows as a massive portrait of Mercer hanging on the wall of the hallway or similar? Finally, I don't think we should necessarily see the mouse running after the butler; the joke might work better if we just see the mouse on the suitcase already, otherwise you're basically giving your punchline away a bit prematurely.