Demons of Air and Darkness is a Star Trek: Deep Space Nine novel by Keith R.A. DeCandido published by Pocket Books in 2001. The novel is the fourth book in the DS9 relaunch, and fourth book in the Star Trek: Gateways crossover miniseries. The story centers on the planet Europa Nova, which is suffering deadly radiation bombardment from a Malon freighter dumping waste into an Iconian gateway. Like all the novels in the Gateways series the story ends with a cliff-hanger, which is continued in a novella, "Horn and Ivory", in the seventh book in the series What Lay Beyond. and was reprinted in the omnibus Twist of Faith in 2007.