tech advise on dracula cape with frame...

I need some ideas on how to properly achieve an effect in the stage version of Dracula...the Hamilton Dean and John Balderston one. I am trying to figure out how to achieve the effect of when dracula is grabbed, and he really goes into the trapdoor and dissappears, but there is some sort of frame under his cape so that when people grab it, it looks like hes still int it. I thought for sure there would be someones productions notes of costume designs for this but apparently not many theatres HAVE a tapdoor, and therefore do it differently. Any inout/drawings/suggestions appreciated.