Crystal Doors #3: Sky Realm (No. 3) by Kevin J. Anderson, Rebecca Moesta

illnesses, debilitating diseases.
    The Vizier said plainly, “Poison. An assassin got past our testers.”
    “We caught the assassin,” the Sultan coughed, sounding angered at the thought of the man. “But it was too late. The poison was already inside me.”
    “Poison.” Tiaret looked around, on her guard. “Has the prisoner been interrogated?”
    “Yes, and executed,” Jabir said.
    “But why would anyone want to kill your father?” Vic said.
    From his bed, the Sultan let out a dry chuckle. “I do not have time enough left to live to explain all the reasons. Imagine hundreds of different factions and families, all of whom have their own needs and desires.”
    “Our flying city has been plagued by more and more frequent attacks by leathery demons called the terodax,” the Vizier explained when the Sultan could not summon the strength to continue. “The batwinged creatures were once primitive predators but are now advanced enough to build aeries. They want to attack and kill everyone on Irrakesh and take our city as a great floating nest for their own kind. There is no reasoning with the terodax.”
    “And one of these things poisoned the Sultan?” Gwen asked, trying to follow the story.
    The Vizier shook his head. The Sultan leaned forward on the bed. “No, it is because I sent messages to the aeglors, hoping to form an alliance to protect Irrakesh. Their leader King Raathun said that — for a price — the aeglors would help defend our skies.”
    Gwen looked from the Sultan to the Vizier to Sharif. “Are they from this world? And what are aeglors?”
    “Both terodax and aeglors share this world with Irrakesh,” Sharif said. “The aeglors look human, but with large feathered wings on their backs. They are also more barbaric than our culture here, though we have much more in common with the aeglors than we do with the terodax, who are not at all human.”
    “Okay, let me get this straight,” Gwen said. “First, these terodax are preying on the city, right? Second, you’re asking the eagle-winged people to help you protect Irrakesh. Third, someone poisoned you because of that?”
    The Vizier tugged on his braided beard. “There is a longstanding feud between the aeglors and Irrakesh. No love is lost between us and the eagle-winged men. Many of our noble families resent the very idea of striking a bargain with them.”
    “Sheesh. Security first, pride later, I say. If it saves Irrakesh, who cares?” Vic asked. “Can’t they agree to fight a common enemy?”
    “It is a matter of honor. In Irrakesh, blood runs hot when dignity is not properly addressed.”
    Jabir continued to explain, “The Sultan is in constant danger, so we use wards and spells to identify any poison in his food or drink.”
    “Sounds like you needed to do a better job,” Vic muttered.
    “The assassin did not use a poison that could be detected. The Sultan consumed an in ert powder during an extravagant banquet, after which the assassin worked a catalyst spell to convert the innocuous substance into a powerful venom. The Sultan would have died that night, so potent was the deadly chemical, but once the toxin was activated I detected it and concocted an antidote —”
    “Then why is my father not cured?” Sharif demanded.
    “Alas, Prince Ali, the antidote is but temporary. It can only neutralize the venom for a short time. Poison has sunk its claws into your father’s system. It cannot be removed. Each day he must consume more of the antidote just to function.”
    “Just to stay alive.” From his bed, the old Sultan coughed. “The assassin belonged to a noble family, many of whose sons had been killed in previous skirmishes with the aeglors. They would rather see Irrakesh crash to the surface in utter destruction than forgive the aeglors.”
    “That’s ridiculous,” Gwen said. “They sound like fanatics.”
    “They are deeply offended. Their priorities are not comprehensible to outsiders.”
    “They are not