The Last Unofficial Minutes of the Council of They

While on a mission to deliver a personal thank you message from the Council of Them to the Council of They, two couriers from Earth One (or is it Earth Two?) find a metal box where Earth Two (or is it Earth One?) used to orbit the sun. Upon return to Earth One (or is it Earth Two?) the box is opened and the mystery of whatever happened to Earth Two (or is it Earth One?) is explained--I think.