Demons of Air and Darkness
Once they moved from world to world in a single step, through innumerable doors that spanned the galaxy. They were masters of space, and to those who feared them, they were demons of air and darkness. But long ago they left their empire and their miraculous technology behind. Now someone has found the key to it, and all those doors have been flung open.
GATEWAYS
DEMONS OF AIR AND DARKNESS
A world near Deep Space 9, 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.
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Keith R. A. DeCandido
Keith Robert Andreassi DeCandido (born 1969) is an American science fiction and fantasy writer.
While Keith R. A. DeCandido is best known for his Star Trek fiction, he has written tie-ins for other popular science fiction and fantasy series as well, such as Buffy the Vampire Slayer, Doctor Who, Supernatural, Andromeda and Farscape, as well as comic books (Spider-Man) and videogames (World of Warcraft, Starcraft, Command & Conquer). He has also edited various anthologies, including OtherWere, Urban Nightmares, Imaginings, the Doctor Who collection Short Trips: The Quality of Leadership, and the Star Trek anthologies New Frontier: No Limits, Tales of the Dominion War, and Tales from the Captain's Table.
Star Trek: Gateways
Star Trek: Gateways consists of seven books. The current recommended reading order for the series is provided below.
Main series Star Trek Crossovers

