4th book of 7 in the Star Trek: Gateways series and known as the Deep Space Nine volume.
"A world near Deep Space Nine, threatened with destruction from the distant Delta Quadrant, becomes the focus of a massive rescue effort as Colonel Kira Nerys, her crew, and some unexpected allies fight to avert disaster on a planetary scale. Meanwhile, as Lieutenant Nog and Ensign Thirishar ch'Thane search for a way to shut down the spatial portals forever, Quark becomes involved in a dangerous game that could determine, once and for all, who will control the Gateways."
Note: Garak plays a small part.