The Wounded Sky (Star Trek, No 13)

An alien scientist invents the Intergalactic Inversion Drive, an engine system that transcends warp drive -- and the U.S.S Enterprise? will be the first to test it! The Klingons attempt to thwart the test, but a greater danger looms when strange symptoms surface among the crew -- and time becomes meaningless. Now Captain Kirk and his friends face their greatest challenge -- to repair the fabric of the Universe before time is lost forever!