Book #9 in the Star Trek Deep Space Nine series of books from Pocket Books.
"The free flow of traffic to the Gamma Quadrant is vital to the recovery and survival of the planet Bajor and to Federation interests as well. When a mysterious cloaked ship begins raiding wormhole shipping, cleaning out holds and killing entire crews, Commander Benjamin Sisko of Deep Space Nine? acts at once to stop the menace."
Note: Elim Garak plays an important role.