Callie shrugged. “Of the thousand and a half bands of Liars we’ve met, whether it’s a dozen on a small ship or a civilization of millions settled on another planet, each group has a different story about their origins, their goals, and the nature of the universe. Every time they’ve claimed to have an ancestral homeworld, and we’ve gone to look, we’ve found an uninhabited rock where nothing like the Liars could have plausibly evolved – and sometimes there’s no planet there at all. The Liars often claim there are lots of other intelligent alien species in the universe, but we’ve never met any of them, or seen any signs.”

Elena rolled the mug back and forth between her hands, a worry line creasing her forehead. “I don’t understand. What do they say when they’re caught in a lie? Do they offer any explanation?”

“Oh, sure. They say the lies are translation errors, or that we talked to heretics from a doomsday religion, or that our ambassadors are mentally ill pathological liars, or that our feeble human minds can’t comprehend their truths, or that we must have followed their directions incorrectly, or that reality is a glitched simulation. A Liar will tell you the sky on Earth is green, and when you object, he’ll explain that humans just have inferior color receptors. They’re absolutely unflappable and endlessly adaptable and totally infuriating and they’ve driven generations of xenopsychologists to the brink of madness.”

Elena looked troubled. Callie had grown up knowing about Liars, but she could imagine how hearing about the aliens for the first time would be alarming. “If the only thing they have in common is lying, then clearly they have a culture built on lies. Do they lie among themselves, or just to humans?”