The Surprise of Haruhi Suzumiya (light novel)

Where Haruhi goes, trouble follows!
The two storylines from The Disassociation of Haruhi Suzumiya continue, introducing a new inductee into the S.O.S. brigade who may be more than just the eager freshman she appears to be. As the two realities converge, the SOS Brigade learns that the new member may have the ability to bring the two story "timelines" together... and save the world in the process.
This book was originally published as two separate volumes in Japan, but the U.S. version will feature both volumes for the price of one.