C.J. Cherryh

Chronicles Of Morgaine

• Gate of Ivrel

• Well of Shiuan

• Fires of Azeroth

by C.J. Cherryh. 

The alien Qhal discovered a gate on a moon by which they could travel instantly to other worlds.

They built a system of gates and used them to travel not just in space but in time, but then someone went backwards in time and reality collapsed. 

Humans, who had been tangled by the Qhal, discovered the gates and sent out a mission to close them and prevent reality from collapsing further. 

Morgaine is the last survivor of this mission, and she’s grimly determined to keep on with it, no matter what it takes.