The Rath Cycle is contained within the anthology Rath and Storm. It follows the story of the Weatherlight on their adventure into the artificial plane Rath and back again. Each story is told from a different character's background and perspective, illuminating their roles and personalities each in turn.
It takes place during Tempest block, several years after the events of Weatherlight. Captain Sisay has recently been kidnapped by an old "acquaintance" of Gerrard Capashen's who recently became evincar of Rath, and begins with the crew trying to convince him to come to Rath with them. From there, they planeshift to Rath, where they find why the evincar lured them there, and that their homelands are in more danger than they could ever fathom.
The Rath Cycle was also pictured in the comic Gerrard's Quest.