What would the MacGuffin be for my story involving Ivan the Terrible? I wrote a fictional item called the cross of the seven jewels. But I have no idea what it is nor the history behind it. Any help would suffice. The story is set in 1904 Russia. Where my main character and his partner are captured by Cossacks and demand them to hand it over. The cross of the seven jewels that is. It somehow connects to the supernatural/paranormal.