Tetralogy

A tetralogy (from Greek τετρα- tetra-, "four" and -λογία -logia, "discourse") is a compound work that is made up of four distinct works. The name comes from the Attic theater, in which a tetralogy was a group of three tragedies followed by a satyr play, all by one author, to be played in one sitting at the Dionysia as part of a competition.