The myth of Osiris and Isis comes from Egyptian mythology. They were a couple in love. Their brother, Set, usurped Osiris' throne by cutting Osiris up into 14 pieces and scattered them all over the world. Isis gathered the pieces in order to have a son posthumously with Osiris. This child's name was Horus.
This holds a digit to the coordinates of the final cache of the series, Horus.