Definition of Fear series

The "Fear Series," or as it's more commonly known among Rush's fanbase, "The Fear Trilogy," is a set of four songs by the band Rush. The series consists of Part I: The Enemy Within (from Grace Under Pressure), Part II: The Weapon (from Signals), Part III: Witch Hunt (from Moving Pictures), and Part IV: Freeze (from Vapor Trails). Parts I, II, and III were released in reverse order, while Part IV was released almost twenty years after Part III. The songs do not follow a set storyline; instead, they deal with topics relating to the emotion of "fear".