Diana says that the power of Tresum has been dammed up since Grace 's wedding to Ambrosius was cancelled and Grace says that come the Solstice all the blocked power will flow into her .
Grace confronts Diana and it 's revealed that they are sisters .
Diana says that the power of Tresum has been dammed up since Grace 's wedding to Ambrosius was cancelled and Grace says that come the Solstice all the blocked power will flow into Grace .
Grace confronts Diana and it 's revealed that they are sisters .