What happened in the unseen labyrinth to which the pneumatic tubes led, he did not know in detail, but he did know in general terms.
On impulse he had turned away from the bus-stop and wandered off into the labyrinth of London, first south, then east, then north again, losing himself among unknown streets and hardly bothering in which direction he was going.
There are no more uses of "labyrinth" in the book.
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The gutted structure crouches like a wounded animal amid a labyrinth of crumbling dwellings.
Sabaa Tahir -- An Ember in the Ashes
"I heard Mom say that the warlocks of the Spiral Labyrinth have been looking for a way to reverse the effects of the Infernal Cup," said Isabelle.