Three-parter (7)
I believe the answer is:
trilogy
(Other definitions for trilogy that I've seen before include "Set of three literary or dramatic works" , "collected works" , "Story in three parts" , "series" , "Group of three linked works" .)
I believe the answer is:
trilogy
(Other definitions for trilogy that I've seen before include "Set of three literary or dramatic works" , "collected works" , "Story in three parts" , "series" , "Group of three linked works" .)