"A riddle is a traditional test of mental agility," says the sphinx.

Combeferre nods. "Yes, and locating our friends would test your mental agility, would it not?"

He takes a sandwich from Joly and sniffs at it. Ham and cheese. "Do have a sandwich," he adds politely, handing it to the sphinx.

The sphinx regards it dubiously.

"Hospitality is an important tradition, is it not?" Combeferre says, when the sphinx hesitates just a moment too long.

The sphinx gives Combeferre a glare, and then opens his mouth, leans forwards, and takes the sandwich in his teeth.